Abu Dawud

Benefits and Issues:
Benefit: This narration is very well-known among the jurists (fuqaha).
But in reality, from the perspective of its chain of transmission (isnad), it is completely weak.
None of the scholars of hadith criticism and evaluation (jarh wa ta'dil) have authenticated it. Three reasons have been listed for its weakness.

➊
It is mursal (a narration with a missing link between the Successor and the Prophet sallallahu alayhi wa sallam).

➋
The companions of Mu'adh are unknown (majhul).

➌
Harith bin Amr is unknown (majhul).
Imam Bukhari says:
“La yasihh wa la yu'raf illa mursal-an” — It is not authentic, and all the known chains are mursal.
Imam Tirmidhi says:
“Hadha hadith la na'rifuhu illa min hadha al-wajh wa laysa isnaduhu 'indi bimutasil” — This hadith is narrated only through this chain, which in my view is not connected (mutasil).
Imam Daraqutni says:
“Wal-mursal asahh” — Its being mursal is more correct.
Ibn Hazm says:
“La yasihh li'anna al-Harith majhul wa shuyukhuhu la yu'rafun” — This hadith is not authentic because Harith is unknown, and his teachers are also not known.
Ibn Tahir says:
“La yasihh” — It is not authentic.
Ibn al-Jawzi said:
“La yasihh” — It is not authentic.
Al-Dhahabi says:
“Wa anni lahu al-sihhah? Wa madaruhu 'ala al-Harith bin 'Amr wa huwa majhul 'an rijal min ahl Hims la yudra man hum” — How can this hadith be authentic? Its axis is Harith bin Amr, who is himself unknown, and he narrates from men of Hims whose identities are not known.
In addition, al-‘Aqeeli, al-Subki, and Ibn Hajar rahimahullah also say the same.
Shaykh al-Albani rahimahullah states:
From a substantive (ma‘nawi) perspective as well, there is a severe flaw in it.
In it, the statement of Mu'adh radi Allahu anhu is mentioned in such a way that he says: First I will judge by the Book of Allah. If I do not find it there, then by the Sunnah of the Messenger of Allah sallallahu alayhi wa sallam. If I do not find it there either, then I will use my opinion (ra’y). However, this sequence and the separation between Qur’an and Sunnah is not correct in any way.
Rather, it is obligatory to refer to the hadith and Sunnah alongside the Noble Qur’an.
Because the Sunnah explains the concise (mujmal) aspects of the Noble Qur’an,
restricts the absolute (mutlaq), and specifies the general (‘amm).
In short, this sequence is not correct.
Rather, every issue should be sought in both the Qur’an and Sunnah at the same time.
Then, the fatwas and practices of the best generations — the Companions radi Allahu anhum ajma‘in, the Followers (Tabi‘in), and the Followers of the Followers (Taba‘ Tabi‘in) — should be considered.
If it is not found, then a person of knowledge has the right to derive, deduce, and exercise ijtihad.
(Taken from Silsilat al-Ahadith al-Da‘ifah, Shaykh al-Albani, Volume Two, Hadith: 881)

Urdu Footnote:
Note:
(In the chain of narration, "al-Harith ibn Amr" and "rijal min ashab Mu'adh" are unknown narrators.)