I will follow the same procedure as in my answer on Are these narrations of Ibn as-Sunni authentic? (Part 1). Just for your information the typical chronology of my research procedure however is searching for the hadith in ibn as-Sunni's book, checking the narrator chain then checking the authenticity qualifications of scholars. This needs to be said in order to avoid a misunderstanding due to some possibly wrong or strange commentaries (my own conclusions or guesses) when presenting the narrator's biographies.
Analysis of the narration: "Ashahdu an laa Ilaha ill Allahu ar-Rahmaanu ar-Raheem..."
The full narrator chain from the book of ibn as-Sunni
In ibn as-Sunni's book 'Amalu al-Yawmi wal-Laylah the hadith appears under the chapter of what one says after the prayer of as-Sobh (fajr fard):
Please note in the following I'll be translating from Arabic language, as these translations are of my own take them carefully!
112 - أخبرنا سلم بن معاذ، حدثنا حماد بن الحسن بن عنبسة، حدثنا أبو عمر الحوضي، حدثنا سلام المدائني، عن زيد العمي، عن معاوية بن قرة، عن أنس بن مالك، رضي الله عنه قال: كان رسول الله صلى الله عليه وسلم إذا قضى صلاته مسح جبهته بيده اليمنى، ثم قال: «أشهد أن لا إله إلا الله الرحمن الرحيم، اللهم أذهب عني الهم والحزن» (Source)
We were informed by Salm ibn Mu'adh, from Hammaad ibn al-Hassan ibn 'Anbasah, from abu 'Umar al-Hawdy, from Sallaam al-Madaa'iny, from Zayd al-'Ammiy from Mu'awiyah ibn Qurrah, from Anas ibn Malik who said: When the Messenger of Allah, may Allah’s prayers and blessings be upon him, completed his prayer, he wiped his forehead with his right hand, then said: "I bear witness that there is no god beside Allah, the (most) Beneficent, the (most) Merciful. O Allah, remove worry and grief from me"
It seems that at-Tabarani quoted the hadith in his al-Majma' al-Awsat. And it was also compiled by abu Na'im in his al-Hilyah and further in al-Amali. But they all rather quoted the supposed weakness of Zayd al-'Ammiy and remained silent about others.
This hadith assuming it has any authentic qualification could be used as an evidence for wiping the forehead after the prayer (to make it clear at this stage already: this is not confirmed). The wording of the du'a has no issues nor conflicts with the qur'an or sunnah.
The main issue as it seems to me is the related act: wiping the forehead and
the "timing": after (each) a prayer. Both appear also in as-Silsilah a-Da'ifah from a hadith compiled by at-Tabarani in al-Awsat, which ibn Hajar also addressed and got the same qualification: hadith #660 which has a difference in the wording of the du'a:
660 - " كان إذا صلى مسح بيده اليمنى على رأسه ويقول: بسم الله الذي لا إله غيره الرحمن الرحيم، اللهم أذهب عني الهم والحزن ".
Some qualifications and analysis of scholars on it
An-Nawawi mentioned this hadith in his al-Adhkar (see #193 here) without leaving a qualification. While al-Arnaout added the comment: that this isnaad is da'if (which will become clearer when we check our narrator chain).
Ibn Hajar al-'Asqalani quoted many sources and versions of this hadith and added to the commentaries of abu Nu'aym (who regarded this hadith as a strange narration reported via Mu'awiyah ibn Qurrah) and others the most important statement that the version of ibn as-Sunni is very weak due to Sallaam al-Mada'iny (at-Tawyl). See here an edited page from Nata'ij al-Fikr (Vol2/ page 301)
Al-Albani quoted in his as-Silsilah a-Da'ifa at least two versions #1058 and the longer #1059 which he declared both as fabricated (#1058 -which is our discussed hadith- due to Sallam al-Mada'iny also known as at-Tawyl -the tall- and #1059 due to Dawod ibn al-Muhbar who fabricated a whole book called "al-'Aql" العقل. Therefore a-Dhahabi regarded this hadith reported via him in Sunan ibn Majah as a blot for this hadith compilation) and said it is da'if jiddan.
So beside the issue claimed above certainly the huge doubt of this being correctly attributed to the prophet () or even as a report on the authority of Anas ibn Malik () is making this very weak.
- Salm ibn Mu'adh سلم بن معاذ: lived in Damascus and died apparently 315 a.H., he was declared as trustworthy in ibn 'Asakir's Tareekh Dimashq (see here) and by abu Bakr al-Baghandy أبو بكر الباغندي according the database (see here), however if this is true either Salm ibn Mu'adh must have died and lived earlier or al-Baghandy's statement is about a different person as al-Baghandy himself died 312 a.H. and lived in al-'Iraaq according to a-Dhahabi's Siyar 'alaam an-Nubalaa' (See here), I couldn't find anything saying that both met, another strangeness here, is that a-Dhahabi usually quotes some ahadith which he memorizes with a chain via the person whom's biography he is presenting and here he referred to a hadith in Sahih Muslim without quoting abu Bakr this looks like a quote out of context I'm not even sure that there was an exchange between him and imam Muslim, but they have some common teachers. He (Salm) was a teacher of ibn as-Sunni and a Student of Hammaad ibn al-Hassan ibn 'Anbasah.
- Hammaad ibn 'Anbasah حماد بن الحسن بن عنبسة: died according to ibn al-Jawzi in his al-Muntadham (see here) 266 a.H. and he was qualified as sadooq by ibu Hatim and as trustworthy by a-Draqotni and ibn Hajar (see in the database here). He was a student of abu 'Umar al-Hawdy (also known as Hafs ibn 'Umar al-'Azady).
- Abu 'Umar al-Hawdy أبو عمر الحوضي: is regarded as of the trustworthy scholars from Basra, abu Dawod and al-Bukhari reported from him (directly) and an-Nasa-i and al-Bukhari reported from him via intermediate according to a-Dhahabi in his Siyar (see here). He was a student of Sallaam al-Mada'iny (also known as Sallaam ibn Salm -also Saleem or Sulaym- at-Tamimy) See also in the database.
- Sallam ibn Salm al-Mada'iny سلام بن سلم المدائني: He seems to be regarded as matrook (rejected): I couldn't find any scholar considering him better than da'if Yayha ibn May'in was reported to qualify him as da'if and one shouldn't write his hadith in Tareekh Baghdad of al-Khateeb al-Baghdadi (see #4774 here) he also was quoted in the books on Dua'fa' of both an-Nasa-i and al-Bukhari. The database quotes a hard statement of ibn al-Jawzy saying "He reports from trustworthy people fabrications as if it was intentional", while ibn 'Ady said he reports mostly from weak narrators. Among his teachers you may find Zayd ibn al-Hoory al-'Ammiy.
- Zayd al-'Ammiy زيد العمي: He is among the younger Tabi'yn. He's overall qualification is rather da'if. Ibn Hebban says he reported from Anas ibn Malik some fabrication, Yahya ibn May'in and abu Hathim ar-Razi said he is da'if, but his hadith can be noted, abu Hathim added, but his hadith can't be used as evidence (without backup). See for example in Arabic wikipedia and the database. He was a student of both Mu'awiyah ibn Qurrah and Anas ibn Malik ().
- Mu'awqiyah ibn Qurrah al-Muzni معاوية بن قرة المزني: (37 a.H. - 113 a.H.) was a student of many Sahabah (among them Anas ibn Malik, a-Dhahabi expressed some doubt about his narration from 'Ali ibn abi Talib) beside al-Hassan al-Basri and other Tabi'yn. He was qualified as trustworthy by ibn May'n, ibn Hebban, abu Hathim, an-Nasa-i and ibn Sa'ad ... as stated in the Arabic wikipedia, a-Dhahabi's Siyar and in the database.
Analysis of the narration: Allahuma ighfirly dhunuby wa Khtaayaaya kullaha ...
The full narrator chain from the book of ibn as-Sunni
116 - أخبرني علي بن محمد المربعي، حدثنا إبراهيم بن القعقاع، حدثنا عاصم بن يوسف، حدثنا قطبة بن عبد العزيز، عن الأعمش، عن عبيد الله بن زحر، عن علي بن يزيد الألهاني، عن القاسم، عن أبي أمامة، قال :ما دنوت من رسول الله صلى الله عليه وسلم في دبر صلاة مكتوبة ولا تطوع، إلا سمعته يقول: «اللهم اغفر لي ذنوبي وخطاياي كلها، اللهم أنعشني، واجبرني، واهدني لصالح الأعمال والأخلاق، إنه لا يهدي لصالحها، ولا يصرف سيئها إلا أنت» (Source)
I was informed by 'Ali ibn Muhammad al-Murba'iy, from Ibraheem ibn al-Qa'aqaa'a, from 'Asim ibn Yusuf, from Qutbah ibn 'abd al-'Aziz from al-'A'amash from 'Ubayd ibn Zahr from 'Ali ibn Yazeed al-'Alhaany from al-Qassim from abu Umamah who said: "I never came near the Messenger of Allah Allah's prayers and blessings be upon him, after an obligatory or optional prayer without hearing him say: "O Allah, forgive all my sins and transgressions. O Allah, invigorate me, restore me and guide me to virtuous deeds and character for none guides to the virtue thereof and none wards off the evil thereof but You".
Again here the wording of the du'a is in no conflict with the teachings of the qur'an or sunnah (see for example in Sahih Muslim).
The hadith also appears in at-Tabarani's al-Kabir see in #7811, #7893 on the authority of abu Umamah (). And in #3875 on the authorithy of abu Ayyub al-Ansary ().
Some qualifications and analysis of scholars on it
Imam an-Nawawi mentioned the narration without any further commentary in his al-Adhkar (see #194 here). Al-Arnaout however commented it saying: It's isnaad is weak.
In his Nata'ij al-Afkar ibn Hajar mentioned his qualification in Volume 2 page 302ff comparing two major chains of the hadith. See here some edited pages:
His first statement about the hadith is that it is gharib (strange) however he added also: abu 'Abd ar-Raheem (apparently appears in a the narrator chain of at-Tabarani) is agreed upon to be qualified as of a certain trust. While 'Ubayd ibn Zahr (in the version of ibn as-Sunni) is qualified to be da'if by more people than those who disagreed. And their teacher 'Ali ibn Yazid (Al-Alhaany) is agreed to be qualified as da'if and all narratives of this hadith go back to him.
There is another version of the hadith compiled by at-Tabarani which doesn't include the words:
اللهم أنعشني، واجبرني
O Allah, invigorate me, restore me
Which al-Haythami commented it saying it's narrators are narrators of the sahih except with az-Zubayr ibn Khareeq الزبير بن خريق who is trustworthy (See here or here, however the hadith narrated via az-Zubayr ibn Khareeq doesn't include the first part of the du'a at all as you may see here).But ibn Makula said he (ibn Khareeq) has some weakness and has not much narrations. Abu Dawod only mentioned one hadith reported via him (see here) and commented it (maybe in a different work) that he doesn't regard him as a good narrator. And this was the opinion of ibn Hajar and Mughlatay.
Neverthless al-Albani counted it hassan in his Sahih al-Jami' as-Saghir wa Ziyadatihi صحيح الجامع الصغير وزيادته hadith #1266 without any commentary.
My interpretation is that al-Albani might have qualified the hadith as hassan due to the many different narratives supporting it and maybe he restricted it on the last part of the hadith (it would be then hassan lighayrih). This might be a good guess, as in his book he only quoted ahadith contents with a one word qualification without any details and the qualification is not specific for the version of ibn as-Sunni, rather it also includes the versions on the authority of abu Ayub al-Ansari ().
- 'Ali ibn Muhammad al-Murba'iy علي بن محمد المربعي: Here we start by a teacher of ibn as-Sunni who is unknown, as his only known narrator was ibn as-Sunni according the database and his two teachers were Ibraheem ibn al-Qa'aqa'a and Isma'il ibn Muhammad al-'Udhry.
- Ibraheem ibn al-Qa'aqa'a إبراهيم بن القعقاع:(died 265 a.H.) Is mainly regarded as trustworthy as mentioned by al-Khateeb al-Baghdadi in his Tarikh Baghdad (see #3136 here) and a-Dhahabi in his Tarekh al-Islam (see #100 here) and in the database. He is a known student of 'Asim ibn Yusuf.
- 'Asim ibn Yusuf (al-Yarbu'iy) عاصم بن يوسف اليربوعي: (Died 220 a.H.) al-Bukhari, an-Nasa-i and at-Tirmidhi have reported from him in their hadith compilations. He is considered as trustworthy as stated by al-Mizi in his Tahdeeb al-Kamal (see #3031 here) and in the database. He was a student of Qutbah ibn 'Abd al-'Aziz.
- Qutbah ibn 'Abd al-'Aziz : He was declared as trustworthy by Ahmad and ibn Ma'yn according to a-Dhahabi in his Tareekh al-Islam (see #327 here) and confirmed his narration from al-'A'amash. Al-Bazzar declared him as-Salih but not Hafidh and ibn Hajar as sadooq according the database. See all so in Tahdeeb al-Kamal biography #4881.
- Al-'A'amash الأعمش: His name is Sulayman ibn Mahran سليمان بن مهران (61 a.H. -148 a.H. according Arabic wikipedia). He is mainly regarded as a Hafidh and trustworthy as you may read in a-Dhahabi's Siyar (see here) or in the database. One of his students was 'Ubayidallah ibn Zahr.
- 'Ubaydallah ibn Zahr عبيد الله بن زحر: It is difficult to give a main qualification on this narrator,but he is rather weak than being of an acceptable level of trust: Ibn Hajar qualifies him as sadooq, imam Ahmad qualified him once as da'if and elsewhere as trustworthy, ibn Ma'yin is rather of the opinion that he is da'if, ibn al-Madiny even qualified him as munkar al-Hadith , may considered his hadith as lenient لين الحديث, a-Dhahabi said he is ja'iz al-Hadith (which sounds to me like acceptable) and abu 'Abdullah al_Hakim from Nishapure even says that his narration from 'Ali ibn Yazid is a false copy! He is a student of 'Ali ibn Yazid al-Alhaany. See also in the database and in a-Dahabi's Tareekh al-Islam biography #169.
- 'Ali ibn Yazid al-Alhaany (died 113 a.H.) the overall qualification of scholars about him is rather bad as he is regarded as da'if or rejected, al-Bukhari considered him as munkar al-Hadith (according al-'Uqayli, see here. He was student of at least three Qassims: al-Qassim ibn 'Abd ar-Rahmaan al-Hudhaly (the son of ibn Mas'ud()) died 116 a.H., al-Qassim ibn 'Abd ar-Rahmaan a-Shamy (who met abu Umamah()) 112 a.H., al-Qassim ibn Muhammad at-Tamimi 35-106 or 107 a.H. (a grand son of abu Bakr() and one of the 7 scholars of al-Madina from among the Tabi'yn). See also in the database.
- Al-Qassim ibn 'Abd ar-Rahmaan a-Shamy : There's a huge disagreement about him, al-Bukhari regarded him as trustworthy, however imam Ahmad even said that Yazid narrated from him strangeness which origin he identified by al-Qassim, abu Hathim ar-Razi said that the narration of trustworthy scholars from him is fine, but those of weak narrators is to be rejected Ibn Hebban said he reported from the sahabah faulty things and pretended to have met 40 of the people of Badr. A-Dahahabi considered al-Bukhari's statement in his Tarekeh that he met 'Ali () and ibn Mas'ud () as a mistake and Ahmad doubted him to have met Salman al-Farisi (). The authors of the four Sunan reported from him and al-Bukhari in his al-Adab al-Mufrad. See for example in as-Siyar, in the database and Arabic wikipedia
In this chain we have many narrators which have an ambivalent qualification however already the teacher of ibn as-Sunni is rather unknown, so on the whole it is pretty much clear why the version of ibn as-Sunni should be regarded as very weak. However there are versions or narrations that support it and could rise it to the level of an acceptable (da'if) or maybe even hassan hadith, but this would be a different topic.