Many writers – especially in the present age – despite their differing madhabs and specialities – are in the habit of quoting Ahaadeeth attributed to the Prophet (s.a.w.s) – without declaring those which are weak there from, out of ignorance of the Sunnah, or desiring that, or being too lazy to refer back to the books of the experts in that field – and some of those experts are lenient in that about narrating Ahaadeeth about excellent actions. Aboo Shaamah said [‘al-Baa’ith ‘alaa Inkaar il-Bida’ wal-Hawaadith’ p.54] :" And this is with the verifiers of the scholars of Ahaadeeth and with the scholars of Usool and Fiqh a mistake, rather they should make its status clear if known – and if not then that will fall under the threat in his (s.a.w.s) saying : " He who narrates from me a saying which he thinks is a lie, then he is one of them. " Reported by Muslim.
This is the ruling for one who remains silent about weak Ahaadeeth concerning excellent actions!
Then how about that which concerns rulings and its like?
And know that this done by one of two men : -
(1) Either he knows the weakness of those Ahaadeeth and he does not indicate their weakness – then he does not indicate their weakness – then he is one who deceives the Muslims, definitely entering under the aforementioned threat – as Ibn Hibbaan says in his book ‘Ad-Du’afaa’ (1/7-8).
" In this narration is a proof that if the Muhaddith narrates something which is not authentic from the Prophet (s.a.w.s) from what is attributed to him incorrectly and he knows that – then he is like one of the liars – and the text of the narration is even stronger than that, he (s.a.w.s) said : " He who narrates Ahaadeeth form me and he thinks it is a lie.. "and he did not say : " Which he is sure is a lie", so everyone who doubts about what he narrates whether it is authentic or not – then he falls under the address of that narration.
And Ibn ‘Abdul-Haadee quotes this in ‘as-saamirul-munkee’ (p.165-166) and agrees to it, or that he does not know that is it weak - and he is also sinful due to his taking it upon himself to attribute it to the Prophet (s.a.w.s) without knowledge, and he (s.a.w.s) said :
" It is enough falsehood for a person that he narrates everything which he hears" [Reported by Muslim in the introduction of his ‘saheeh’ see ‘as-saheehah, no. 205].
So he has his share of the sin lying upon the Messenger of Allah (s.a.w.s), since he (s.a.w.s) indicated that he who narrates everything which he hears - and like him is the one who writes is – falls for certain into lying upon him – and therefore he is one of the liars. Firstly – the one who invented it,
and secondly this one who spread it! And Ibn Hibbaan also said (1/9) :
" And this narration contains a strong warning against a person’s narrating everything which he hears until he knows for certain that it is authentic."
And an-Nawawee clearly states that the one who does not know whether Ahaadeeth is weak or not then it is not permissible for him to use it as a proof without researching and checking it if he knows how – or by asking the people of knowledge if he does not know. And refer to the preface of ‘ad-Da’eefah’ (pp.10-12 ).