First of all different scholars when qualifying a hadith come to different conclusions about its authenticity, based on the data they have at hands.
Further a qualification for a specific version of a hadith might differ from a scholars overall position of the hadith content.
Rough source analysis
Secondly let's check sources that include this hadith:
On the authority of 'Ali ibn abi Talib():
- Imam Malik's Al-Muwatta' via the route:
Malik -> ibn Shihaab a-Zuhri -> 'Ali ibn al-Hussain -> 'Ali ibn abi Talib.
- Jami' at-Tirmidhi via the route:
Qutaybah -> Malik (from here same route of al-Muwatta).
A-Tirmidhi commented this as a Mursal because 'Ali ibn al-Hussain never met his grandfather. But a-Tirmidhi regarded this route as better than that of abu Salamah from abu Hurrairah.
On the authority of abu Hurrairah():
- Sunan ibn Majah via the route:
Hisham ibn 'Ammar -> Muhammad ibn Sho'aib ibn Shaboor -> al-Awza'iy -> Qurrah ibn Abdurrahman ibn Haywaiyl -> ibn Shihab az-Zuhri -> abu Salamah -> abu Hurrairah.
- Jami' at Tirmidhi via the route: Ahmad ibn Nasr an-Naysaburi and others (more than one)-> abu Mushar -> Isma'il ibn 'Abdullah ibn Sama'ah -> al-Awza'iy (Same route as ibn Majah).
- The "main" route from Sunan ibn Majah "al-Awzai'y -> ... -> abu Hurrairah" was also compiled by al-Bayhaqi in his as-Sunan al-Kubra (see here)and Shoa'ab al-Iman (see here) and ibn Hebban in his Sahih (see here)to name to rather prominent sources.
On the authority of Zayd ibn Thabit():
- Al-Mu'ajam as-Saghir (see here) of imam at-Tabarani among other lesser known sources. In the named book via the route (the common route starts with the narrator marked in bold letters):
Muhammad ibn 'Abdah al-Massisi (abu Bakr) مُحَمَّدُ بْنُ عَبْدَةَ الْمِصِّيصِيُّ أَبُو بَكْرٍ -> Muhammad ibn Kathir ibn Marwan al-Filistyni مُحَمَّدُ بْنُ كَثِيرِ بْنِ مَرْوَانَ الْفِلَسْطِينِيُّ -> 'Abdurrahman ibn abi az-Zinad عَبْدُ الرَّحْمَنِ بْنُ أَبِي الزِّنَادِ -> His father (abu az-Zinad) -> Khrajah ibn Zayd ibn Thabit -> His father.
On the authority of al-Harith ibn Hisham():
- Tareekh Dimashq (see here) of ibn 'Asakir and elsewhere. Via the (common) route:
Yahya ibn abi Unaysah يحيى بن أبي أنيسة -> ibn Shihab a-Zuhri الزهري -> 'Ali ibn al-Hussayn علي بن الحسين -> al-Harith ibn Hisham الحارث بن هشام
On the authority of Anas ibn Mailk():
- Via the route in a book of al-Hakim from Nishapur called Sualat as-Sijzy lil Hakim (see here):
Abu al-'Abbas al-Assam ابو العباس الاصم -> Ahmad ibn Shayban ar-Ramly احمد بن شيبان الرملي -> Sufyan ibn 'Uyyanah سفيان بن عيينة -> ibn Shihab a-Zuhri الزهري -> Anas ibn Malik.
On the authority of Usamah ibn Zayd():
- In a book called al-Intikhab الانتخاب of abu Tahir a-Silafi أبو طاهر السِّلَفي (the book doesn't exist in a printed version). Via the route:
'Umar ibn Qays عمر بن قيس -> ibn Shihab a-Zuhri الزهري -> 'Ali ibn al-Hussayn -> Amr ibn 'Uthman عمرو بن عثمان -> Usamah ibn Zayd.
On the authority of abu Bakr():
- in the book Ma'arift a-Shabah of abu Nu'aym (see here). Via the route:
Malik ibn 'Atiyyah مالك بن عطية -> His father -> Abu Rafi'ah al-Fahmi أبي رفاعة الفهمي -> abu Bakr.
Discussion of the routes and sources reliability
The most reliable routes however are the first two: 'Ali ibn al-Hussayn (from His father) from His grandfather and that of abu Hurrairah. And almost all scholars agree that this hadith is mursal (means a narrator is left out unnamed). Some regard the route
Qurrah -> al-Awza'iy -> ibn Shihab -> abu Salamah -> abu Hurrairah
as connected however Qurrah is not a much reliable narrator.
For further information and more details on the sources refer to my main reference for takhreej of the hadith (here in Arabic).
If my interpretation of al-Harith ibn Hisham is correct here again 'Ali ibn al-Hussayn can hardly have met him because he died the the plague of 'Amwaas which happened around 18 a.H..
An overall estimation
As you may see from this rather rough and superficial check all variations of this hadith have some issues. So even if one could come to an overall qualification that it is at least hassan lighayrih (due to backup elsewhere) almost all of the versions could be regarded as da'if by themselves.
Some scholars consider it hassan by itself. Note that the acceptance of mursal hadith was already a matter of discussion in the first 3 centuries.
Sheikh al-Albani when asked about the hadith (not a specific variation or compilation) answered that he regarded it as sahih (My own understanding: in his terminology hassan and sahih are rather similar level) -see here in Arabic-.
High acceptance of scholars
This hadith appears in the 40-Hadith of imam an-Nawawi. This alone should tell that scholars consider this hadith's content as an important statement and teaching of Islam.
Some scholars counted it as a third or fourth of the knowledge (of Islam).
It was quoted that 'Abdullah ibn abi Zayd said:
heer and in the following I'll be translating from Arabic text, as tehse translations are of my own take them caerfully
جِمَاع آدَاب الْخَيْر يَتَفَرَّع مِنْ أَرْبَعَة أَحَادِيث
The collection of good manners is branched out from four ahadith:
(Source 1, 2)
And he counted beside the hadith discussed here the following three ahadith among them:
"Whoever believes in Allah and the Last Day should talk what is good or keep quiet, ... "(See for example in Sahih al-Bukhari)
"Do not become angry and furious." ... (See for example in Sahih al-Bukhari)
""None of you will have faith till he wishes for his (Muslim) brother what he likes for himself."" (See for example in Sahih al-Bukahri)
Abu Dawod the author of the Sunan also wrote or was quoted to having said or written the following:
كَتَبْت عَنْ رَسُول اللَّه صلى الله عليه وسلم خَمْسمِائَةِ أَلْف حَدِيث، الثَّابِت مِنْهَا أَرْبَعَة آلاف حَدِيث, وَهِيَ تَرْجِع إِلَى أَرْبَعَة أَحَادِيث
I wrote on the authority of the Messenger of Allah, Allah's prayers and blessings be upon him, five hundred thousand ahadith, of which the established (sane) ones are four thousand, and they are traced back to four ahadith.
Note that I couldn't find some of this quotes in his Sunan * or in a different wording **, my references for these ones will link to a corresponding hadith from the 40 hadith of imam an-Nawawi
قَوْله عَلَيْهِ الصَّلاة وَالسَّلام (إِنَّمَا الأَعْمَالُ بِالنِّيَّاتِ)
His Allah's prayers and blessings be upon him statement "Actions are to be judged only by intentions".
وَقَوْله (مِنْ حُسْنِ إِسْلامِ الْمَرْءِ تَرْكُهُ مَا لا يَعْنِيهِ)
His statement "Part of the excellence of a man's Islam is that he leaves what does not concern him.*"
وَقَوْله (الْحَلالُ بَيِّنٌ وَالْحَرَامُ بَيِّنٌ)
And his statement "What is lawful is clear and what is unlawful is clear".
وَقَوْله (لا يَكُون الْمَرْء مُؤْمِنًا حَتَّى يَرْضَى لأَخِيهِ مَا يَرْضَى لِنَفْسِهِ)
And his statement "A person is not a believer until he consents for his brother what he would like for himself.**"
وَرُوِيَ مَكَان هَذَا (اِزْهَدْ فِي الدُّنْيَا يُحِبَّك اللَّهُ)
And instead of this was also narrated:"Renounce the world and Allah will love you"
(Sources 1 & 2)
Among the verses that support the meaning of this hadith you may often find quoted:
No good is there in much of their private conversation, except for those who enjoin charity or that which is right or conciliation between people. And whoever does that seeking means to the approval of Allah - then We are going to give him a great reward. (4:114)