And know, may Allāh have mercy upon you, that what is obligatory upon everyone who is able to distinguish between authentic and weak narrations and between the suspect and reliable narrators, is that he should narrate therefrom that which is known to be authentic and have trustworthy narrators.
Many of the early scholars held the firm opinion that to act upon, or derive rulings from a ḥadīth that has been declared to be weak, by the scholars of ḥadīth is unacceptable. Their reasoning is that Islām has no need for anything weak, and the authentic material of Islām will suffice for all time, the ḍaʿīf ḥadīth amounting only to a conjecture which has the possibility of being correct.
I quote from the introduction of ‘The Prophets Prayer Described’ of Shaykh al-Albānī, “…this is because I hold that the authentic aḥādīth are sufficient, leaving no need for anything weak, for the latter does not amount to anything except dhann (conjecture, suspicion), and incorrect conjecture at that; as the Exalted says: “…and conjecture is of no use against the truth.”
And now the following quotes will show the position of the early Scholars of Ḥadīth on this issue:
Imām al-Shāfiʿī1 says in his ‘Risālah’ (394-403: #1090-1105),
‘[#1090] Surely, the greatest of liars is he who ascribes to me that which I did not say, and who claims to have dreamt what he did not dream, and who claims that he is the son of someone other than his own father.
[#1091] Whoever ascribes to me that which I did not say, will surely have to occupy his seat in the fire [of hell]
[#1092] Surely, whoever tells untruths about me, will have a house built for him in the fire [of hell].
[#1093] Whoever tells untruths about me is surely seeking for himself a resting place in the fire [of hell]. The Messenger of Allāh began to say that while he was wiping the ground with his hand.
[#1094] From Abū Hurayra, “You may report about the Children of Israel and there is no blame (haraj). Report about (/from) me, but do not tell untruths about me.”
[#1095] This is the most emphatic ḥadīth ever transmitted from the Messenger of Allāh on this matter. We have relied on it as well as on others (aḥādīth or evidence) in not accepting any report (ḥadīthan) except a trustworthy [transmitter], and that we know the truthfulness of those who transmitted the ḥadīth since it was begun till its end is reached.
[#1096] If someone would say: What evidence is there in this ḥadīth for what you have stated?
[#1097] It would be said: Knowledge surely has made it certain that the Prophet would never, in any circumstances, order anyone to lie about the Children of Israel, nor about anyone else. So when he has permitted reporting about (al-ḥadītha ‘an) the Children of Israel, it was not accepting untruthfulness about the Children of Israel that he has permitted, but he only has permitted accepting that from whom reported it, whose truthfulness or untruthfulness is not known.”
Imām Muslim states in the introduction to his ṣaḥīḥ, under the chapter heading, “the weak aḥādīth are to be discarded and only authentic aḥādīth are to be narrated,”
“To proceed, may Allāh have mercy upon you. If it were not from the evil practice that we have seen from many who take upon themselves the position of Muhaddith, in their leaving the obligation to discard the weak aḥādīth and munkar narrations and to suffice with only the authentic aḥādīth – well known and transmitted from reliable narrators, well known for their truthfulness and trustworthiness. After knowing and admitting with their tongues that much of what they fling at the ignorant is to be rejected and is transmitted by unsatisfactory narrators whose narrations are censured by the scholars of ḥadīth like Mālik, Yahya ibn Saʿīd al-Qattaan and others…..
And know may Allāh have mercy upon you, that what is obligatory upon everyone who is able to distinguish between authentic and weak narrations and between the suspect and reliable narrators, is that he should narrate therefrom except that known to be authentic and have trustworthy narrators…”
Imām ibn Rajab al-Ḥanbali2 says, ‘and it is clear from what Muslim mentions in the introduction to his book (i.e. Ṣaḥīḥ Muslim), that it is necessary that the aḥādīth to do with Targheeb wat Tarheeb (encouragement and discouragement) are not narrated except those that aḥkām (rules and regulations) are narrated [meaning the authentic aḥādīth]’
al-Allāmah Jamāl ud-Dīn al-Qasimī narrates from a group of the Imāms of ḥadīth that they did not accept acting by a weak ḥadīth at all, like ibn Maʿīn, al-Bukhārī, Muslim, Abū Bakr ibn al-ʿArabī al-Mālikī, ibn Hazm and others.3
Abū Bakr ibn al-ʿArabī4 said, while commenting on the ḥadīth, “the ḥalāl is clear and the ḥarām is clear”,
“…. What I have [as the reason] regarding that, and Allāh knows best, is that which we have transmitted from Aḥmad ibn Ḥanbal that he permits weak aḥādīth regarding al-wara` (abstaining from doubtful matters). May Allāh be pleased with al-Bukhārī who did not see for the heart to hold to, nor for the religion to be connected through–nothing except the authentic [aḥādīth], and that is our position. If we were to incline to the position of Aḥmad; then holding to ḍaʿīf aḥādīth cannot be [accepted] except in lessons/admonishment which softens the heart, but as for the basis (usūl) there is no way to [accept] that.”5
ibn Hazm6 says in ‘al-Milal’, “and it is not permissible with us that we say as this aḥādīth say (i.e. those weak and fabricated narrations), or to trust in them, or to take anything from them.”
ibn Taymīyyah says, ‘and it is not permissible to rely in the Sharīʿah upon ḍaʿīf aḥādīth which are not ṣaḥīḥ or ḥasan. But Aḥmad ibn Ḥanbal and other scholars considered it permissible to report with regards to Fadaa’il al-A’amaal (rewards and excellences of actions) that which they did not know to be affirmed when it is known that it is not a lie. And that is because when the action is known to be legislated with Sharīʿah evidence, it is possible that the reward is a fact. And not one of the Imāms said that he considered it to be permissible to make something obligatory or recommended based upon a ḍaʿīf ḥadīth.’7
Then ibn Taymīyyah says, ‘and Aḥmad ibn Ḥanbal or others like him from the Imāms did not rely upon this type of aḥādīth in the Sharīʿah. And the one who relates from Aḥmad that he used to rely upon the weak aḥādīth, which are not ṣaḥīḥ or ḥasan, has erred.’
So the narrations from him that he would act upon a ḍaʿīf ḥadīth when there was nothing else present in the texts on that subject, or nothing that contraḍīcted that ḍaʿīf ḥadīth, does not mean that Imām Aḥmad used them as proof in the Sharīʿah. Allāh knows best.
al-Allāmah Aḥmad Shākir says, ‘and as for what Imām Aḥmad ibn Ḥanbal and ʿAbd al-Raḥmān ibn Mahdi, and ʿAbdullāh ibn al-Mubārak said, “when it is narrated to us pertaining to Hʿalál wal Ḥarām we are strict. And when it is narrated to us pertaining to Fadaa’il al-A’maal (the rewards and excellence of actions) then we are lenient.” – then they mean, according to what I find to be most convincing – and Allāh knows best – that the leniency was in their taking the ḥasan ḥadīth, that which does not reach the level of ṣaḥīḥ. Because the convention of distinguishing between the Ṣaḥīḥ and Ḥasan was not present at their time…rather many of the early scholars did not describe a ḥadīth except by it being ṣaḥīḥ or ḍaʿīf only.’8
So what is clear is that the term ḥasan was not present at that time, and a great deal of what these scholars used to narrate in terms of fadaa’il al-amāl was of the level of what the later scholars called ḥasan.
So the opinion of the above-mentioned scholars is to leave acting by the weak ḥadīth in totality, except where there is a consensus of the Islamic scholars on the issue at hand, and Allāh knows best. And as for the claims of some that Imām Aḥmad amongst others of the early scholars allowed weak aḥādīth to be used in Sharīʿah rulings then that has no firm basis as mentioned above.9
And especially in this day and age, when so many innovations and misunderstandings about Religion are present, many of them having their roots in this ḍaʿīf aḥādīth, it becomes even more essential to narrate only authentic aḥādīth as part of the process of purifying the understanding of the Religion.
The preceding was with regards to acting upon the ḍaʿīf ḥadīth, as regards to using the ḍaʿīf ḥadīth in certain Islamic sciences like in the Ḥadīth science in which the weak aḥādīth are used to support or strengthen other aḥādīth, then this has been done and is being done by all of the Scholars of Ḥadīth.
For those that follow the opinion that acting upon a ḍaʿīf aḥādīth is permissible, it would be good to mention the three conditions for acting upon a ḍaʿīf aḥādīth as laid out by Ibn Hajr al-Asqʿalánee:
1) Upon that which they all agree, that it should not be very weak so that it excludes that only narrated by a liar, one accused of lying, and one who makes serious mistakes.
2) That falls under a general proof already present – which excludes that which is invented having no basis.
3) That acting upon it the person does not think that it is something established – in order that he does not attribute to the Prophet what he did not say.10
We can see from this condition the following: The first principle lays out the obligation to make known the weak aḥādīth from the authentic, even in Fadaa’il al-Amāl. Something which many people who follow this opinion do not do, not only that but many of the scholars who follow this opinion today are not even capable of discerning whether the ḥadīth they are quoting contains the types of weaknesses indicated above!
The second principle establishes that in reality, the person is not acting by the weak ḥadīth but rather by the general proof already present.11
 He is the Mujtahid Imām and the Mujaddid of his time, Muḥammad ibn Idrīs al-Shāfiʿī. He studied under a galaxy of prominent Imāms, amongst them Imām Mālik.
 ‘Sharḥ al-Tirmidhī’ (2/112). He is the exemplary Imām and great Mujtahid scholar, ibn Rajab al Ḥanbali, a student of both ibn Taymīyyah and ibn al-Qayyim amongst others.
 ‘Qawā’id al-Ḥadīth’ (pg. 113) of al-Qasimī.
 ‘Aridat al-Aḥwadhī Sharḥ Sunan al-Tirmidhī’ (5/201)
 Quoted from Abū Ghuddas introduction to al-Muhasibi’s ‘Risalah al-Mustarshidīn’ (pp58) where he states that he has abridged the quote from ibn al-ʿArabī.
 He is the great Imām who championed the Dhaahiree School of thought and wrote many invaluable treatises, amongst them his ‘Muhalla’ in usūl al-fiqh, and ‘Milal wa al-Naḥl’ on different sects. He died in the year
 ‘al-qāʾidah al-jalīlah’ (pg.82) of ibn Taymīyyah
 ‘al-Bāʿith al-Ḥathīth’ (pg.101) of Aḥmad Shākir.
 So what would the author of ‘al-Albānī Unveiled’ say about the position of all these scholars, would he label them all as ignorant as well, as he has done in his amazing ‘scholarly’ work?!
 As mentioned by his student as-Sakhāwi in his
 The quotes are taken from the introductions of ‘Ṣaḥīḥ al-Jāmiʿ al-Saghīr’, ‘Tamām al-Minna’, ‘Silsilah al-Ḍaʿīfah’ (Vol. 1) of al-Albānī, with the exception of the quotes of Imām al-Shāfiʿī and ibn al-ʿArabī.