Why do we even quote or keep accounts of weak hadith if they are "weak"? As per my understanding, they are weak because their authenticity is not confirmed because of some reasons. So if there is doubt about them, why don't we totally disregard them?
Weak ahadith can be a proof or confirmation of the health of non-weak ahadith they are further essential additional sources for shar'ia from the perspective of many scholars since the human ratio is not equal to Allah's knowledge or His revelation and its application by the Prophet () and later his companions. Further, it is generally agreed that one is allowed to rely on them virtuous deeds as long as they are not fabricated or extremely odd.
Accoridng to ibn Salah in his مقدمة Muqadimah -Introduction- (see here):
(Here and in the following I'll be mainly translating from Arabic language, with the support of tools and sites like google-translate and al-maany, as in the end, the choice of translation is my own take it with the necessary care!)
كل حديث لم يجتمع فيه صفات الحديث الصحيح، ولا صفات الحديث الحسن المذكورات فيما تقدم، فهو حديث ضعيف.
Every hadith that does not meet the characteristics of an authentic hadith, nor the characteristics of a good hadith mentioned above, is a weak hadith.
وأطنب أبو حاتم بن حبان البستي في تقسيمه، فبلغ به خمسين قسما إلا واحدا، وما ذكرته ضابط جامع لجميع ذلك.
Abu Hatim ibn Hibban al-Busti went into great detail in dividing it, and it amounted to fifty divisions minus one, and what I mentioned is comprehensive and exhaustive of all of that.
Note That the above source helped me a lot in explaining some of the following terms.
To make it clearer I'll list here a couple of conditions that might not be met by a weak hadith with some examples:
- The condition of a connected chain of transmission شرط الاتصال: Examples for such a disconnection are the al-Mu'allaq المعلَّق (see Asalamoalikum! Brother can you tell me about mu'allaq Hadith), al-Mursal المرسَل (Sahabi was not mentioned), al-Munqati'a المنقطِع (one narrator was not mentioned or a meeting between source and receiver is not confirmed), al-Mu'adal المُعْضَل (more than one narrator is missing in the narrator chain) and some add to this al-Mudallas المُدلس (see What exactly is tadlees?)
- The condition of justness (rightefoulness) of the narrator شرط العدالة: Examples for this are hadith Makdhub المكذوب (a narrator known as liar) and al-Matruk المتروك (an abandoned narrator).
- The condition of exactness شرطَ الضبط: examples for this are al-Munkar المنكَر (the refuted), al-Mudarraj المدرَج (this is the case when the hadith contains mixing in which the words of the sahabi who narrated it and the prophet can hardly be distinguished or when a hadith which was narrated by two different rawy's but the continuation quoted is only the version of one of them), al-Maqlub المقلوب (inverted: a narrator was replaced by another).
- The conditions of avoiding odd الشاذُّ narrations (meaning if a narrator -even a trustworthy- narrates something in total opposition to the rest -majority-) and avoiding illnesses العلة (an obvious defect) an example for that is the sahih hadith in the version of an-Nassa-i, where the author quoted 'Amr ibn Dinar عمرو بن دينار (from Mekka) as among the narrtors while all sahih narration say it was 'Abdullah ibn Dinar عبد الله بن دينار (from Medina).
My own 2 cents
First of all there are a lot of things one needs to know:
- The criteria for classifying a hadith are neither carved in stone nor as objective as they may sound but they are subjective or at least the qualifications of scholars are rather subjective due to different reasons, that I want to try to mention. This means yes we may have a general understanding as @Greenix_3 and my definition above pointed at, but some scholars are more lenient than others especially when it comes to the narrator chain (see for example Is there a scale or classification for scholars and their qualification of hadith narrators?) and one hafidh or hadith scholar may have more sources and information available than another. We also need to accept that the people who are checking narrators are human themselves so they may make mistakes, but to avoid this they try to settle a methodology which they try to follow, but they may occasionally fail.
A prominent example of an issue in this regard is the well-known qari' Hafs ibn Sulayman whom's qur'an riwaya is prevalent today many if not all hadith scholars have his name in their books of du'afa' (you may also refer to the Arabic Wikipedia page). How can a qari' whom's qira'a of the qur'an is followed by many people still be considered as righteous if his hadith narration is regarded as fabricated or weak in best case?
Moreover sometimes one would wish that scholars revised their books at some point of their lives. For example, imam a-Dhahabi made a good summary (Talkhees) of imam abu 'Abdillah al-Hakim of Nishapur's al-Mustadrak in his youth that included many qualifications he later revised or even corrected (see for example Is al Hakims Hadith collection Al Mustadrak reliable?).
- The criteria for accepting a hadith in a theological context, especially in regards of fiqh is part of the Osol of a madhhab, for example, both imam's Malik and abu Hanifa would reject an ahad hadith if other non-textual sources were stronger according to their ratio and rigor (on this topic check What are basic (osol al fiqh) differences & similarities between the 4 (existing) Legal Sunni Schools: Hanafi, Hanbali, Maliki, & Shafi'i? Charts? and for the topic of ahad hadith this might be of interest How many ahad hadith are there in Sahih Bukhari?). On the other hand, some madhhabs actually consider the textual sources as more essential (among the four madhhabs the Hanbali's more than the Shafi'i's) some of them would even reject non-textual Osol such as qiyas (analogy) at all like ibn Hazm and the dhahiri's did. In other words for some scholars, if on a topic we have only a weak hadith and nothing else at hand this hadith can be regarded as evidence.
This view besides other reasons had a kind of impact on the theological view of the scholars too so we may find most Hanbali's following the Salafi 'aqidah and Shafi'i's and Maliki's who accept qiyas being mostly Asha'arits and most Hanafi's being Maturidi's.
- In regards to accepting da'if hadith there's only a general agreement for topics where it comes to good or virtuous deeds such as dhikr du'a and so on.
- It must be noted that a hadith as a whole might be weak, but it includes parts which are sahih or hassan. So some of the narrators made incorrect additions this can only be verified by knowing the correct wording.
- You can not differentiate between sahih, hassan, da'if and fabricated hadith if you don't know them and have the possibility or ability to double-check. So by citing side-by-side scholars have shared with us their knowledge over centuries (see also Most hadith scholars had deep knowledge in hadith, why they quoted da'if narrations in their compilations then?).
- Finally, if we find excuses to reject considering dai'f hadith, we may also find similar excuses for rejecting sahih hadith and become qur'anists. Even in regards to sahih hadith we have a kind of classification: Most scholars agree that sahih al-Bukhari is the most sahih book in this context, while imam Muslim's book is somewhat similar but not equal in authenticity, but when it comes to the correctness in wording and Arabic language it is even better than sahih al-Bukhari (We may conclude that some narrators paraphrased what they heard).
But what about other Sahih's like that of ibn Hibban and ibn Khozaimah? We know that both scholars were very lenient in accepting narrators however ibn Hebban at least was a hardliner for weak narrators.
Note that if it were not al-Bukhari and Muslim, but Yahya ibn Sa'id al-Qattan and abu Hatim ar-Razi who compiled a sahih hadith collection we may have had much less sahih hadith and we could be in huge trouble dealing with any kind of hadith since they were known hardliners in their choice of hadith and hadith narrators unfortunately for us is that the first seemingly -as far as I know and Allah knows best- didn't leave any book showing neither his methodology nor his full list of qualification of narrators.
I've also found an article -in Arabic with an English abstract- of Tajuddin al-Abbas in an Indonesian Journal called DIRAYAH Jurnal Studi ilmu Hadits P-ISSN : 2746-1203 E-ISSN : 2746-119X with the title "أهمية الحديث الضعيف ودروره في التشريع والإعجاز العلمي" Published: 2021-04-30 which addresses especially the importance of dai'f hadith in Shari'a and in the topic of scientific miraculousness.
There are reasons on why hadiths are made weak, these are based on the reasons for:
(1) the chain of narrators must be unbroken (in other words, the hadith may be traced all the way back to its source without the names of any narrators missing from the chain); (2) all of the narrators in the chain must be people of integrity and piety; (3) three, all of the narrators in the chain must be either greatly or acceptably proficient narrators; (4) the narration may not contradict stronger reports or narrations; and, (5) there can be no hidden, damaging defect in the chain (for example, if it were discovered that a mistake was committed by one of the narrators).
(refereces messy, so refer to the numbers with >)
The first opinion, as it is generally stated, is that it is allowed to act according to weak hadith in general with virtually no further conditions restricting their use. (1) In reality though, as al-Khudair points out, there are two conditions: the hadith cannot be very weak and there can be no other acceptable and contradictory text on the topic. (2) This opinion is most commonly attributed to and most well-known as being the opinion of Ahmad ibn Hanbal and his close student Abu Dawud, the compiler of the Sunan. Al-Khudair states that this opinion has also been attributed to Abu Hanifah, Malik, al-Shafi'ee and ibn al-Humaam. (3) Ahmad alSideeq al-Maghribi makes the claim that all the leading scholars used weak hadith as acceptable evidence. (4) However, in this abbreviated discussion, the reply to the proofs for this opinion shall be limited to a discussion of Ahmad and Abu Dawood and may be applied by analogy to the other scholars cited above. This conclusion concerning Ahmad's opinion is derived from a number of reports. First and most important is Ahmad's statement, "A weak hadith is more loved to me than a person's opinion." (5) In addition, one time he was asked about a person who had a choice of going to a person who knew hadith but did not know the authentic from the weak or a person who resorted to personal reasoning. Ahmad said that the person should go ask the one who
knew hadith and not the other one. 6 It is also said about him that he would act on the basis of weak hadith if he could not find any other basis to act upon and there was nothing contradictory to the weak hadith. 7 He never resorted to analogy (Ar., qiyaas) unless he found no textual source whatsoever and even then he would prefer to remain quiet than to give his opinion. Similarly, it is claimed that if Abu Dawood found no sahih or hasan hadith on a topic, he would record a weak hadith for he considered that stronger than a person's individual opinion. 8 One interpretation given to Ahmad's statement that weak hadith are preferred over analogy is that it is in reference to a blatantly wrong analogy (qiyaas faasid); that is, an analogy between two actions that do not share important common characteristics or an analogy that violates established principles or rulings of the Quran and sunnah. In such cases, Ahmad would reject the analogy, as is considered acceptable practice by the scholars, and if,that were the only alternative open to him, he would prefer to follow a weak narration. However, an even more important question is the meaning of "weak hadith" in Ahmad's statement quoted above. One thing is certain, Ahmad did not mean by that hadith which are very weak. Ibn al-Qayyim points out that when Ahmad used "weak" hadith, he never used erroneous hadith, munkar ("rejected") hadith or hadith coming from completely non-acceptable sources; he would only use a strong kind of weak hadith, which is similar to what was later called hasan. 9 According to ibn Taimiya and others, before the time of al-Tirmidhi (and Ahmad was before the time of al-Tirmidhi), in general, hadith were divided into only two categories: sahih and dhaeef (weak). However, the dhaeef were of different levels. There were dhaeef that were absolutely rejected and there were dhaeef that were close to but not to the level of sahih. This latter category could be accepted and acted upon. According to this theory, this stronger category of dhaeef is what is known today as hasan. Ibn Taimiya wrote, Weak [among those early scholars] were of two types: weak that cannot be used as evidence, and this is weak in alTirmidhi's terminology, and weak that could be used as evidence, and this is hasan in al-Tirmidhi's terminology. This is similar to the case of two different levels of illness in fiqh.
1 course, no such difference occurs concerning fabricated hadith. It is absolutely forbidden to relate fabricated hadith unless, and only if, it is done to expose the hadith as being fabricated. 2 Abdul Kareem al-Khudhair, Al-Hadeeth al-Dhaeef wa Hukm al-Ihtijaaj bihi (Riyadh: Daar alMuslim, 1 997), p. 250. 3 Al-Khudhair, pp. 25 1 -259. 4 Quoted in al-Khudhair, p. 260. 5 He did not mean very weak or fabricated hadith. This is not the proper place to discuss Ahmad's opinion on weak hadith in detail (as that would take many pages). The interested reader is referred to Abdullah al-Turki, Usool Madhhab al-lmaam Ahmad (Riyadh: Maktaba al-Riyaadh al-Hadeetha, 1 977), pp. 274-281.
6 Ahmad lbn Hajr, al-Nukat ala Kitaab ibn al-Salaah (Madinah: al-Jaamiat al-lslaamiya, 1 984), vol. 1, p. 437. 7 Quoted in Abdul Azeez al-Uthaim, Tahqeeq al-Qaul bi-I-Amal bi-l-Hadeeth al-Dhaeef (alThuqba, Saudi Arabia: Dar al-Hijra, 1 992), p. 30. 8 ibn Hajr, al-Nukat, vol. 1, p. 436. 9 Shams al-Din lbn al-Qayyim al-Jauziya, Ilaam al-Muwaqieen (Beirut: Daar al-Jee!, 1 973), vol. 1 , p. 31.
Weak does not mean fabricated. Weak just means that the hadith sciences can't be used to demonstrate it's authenticity to the highest degree. It honestly says more about the stringency of the verification process than anything about the quality of the hadith itself.
The sunnah of the prophet is evidenced through his words and actions throughout his entire life, not just those few moments that were perfectly recorded and passed down by verifiable channels; there were decades between the first revelation and his death, and every Sahih hadith ever written barely scratches the surface of that time. Many who care about following the sunnah are loathe to lose any of that wisdom he demonstrated, even if it means taking a bit more effort to understand and work out what's actually true through the weaker chains.