The Thirteenth Principle
One must not say of a weak ḥadith, “The Prophet (peace and blessings be upon him) said,” or, “It is reported from him,” and the like.

Al-Nawawī says in al-Majmūʿ Sharḥ al-Muhadhdhab 1/63:

“The meticulous scholars among the experts of ḥadith and others have stated that when a ḥadith is weak it is impermissible to employ categorical wording such as: ‘The Messenger of Allah (peace and blessings be upon him) said,’ ‘did,’ ‘commanded,’ ‘forbade,’ ‘ruled,’ or similar expressions. The same applies to saying of it: ‘Abū Hurayrah narrated,’ ‘said,’ or ‘mentioned,’ and the like. Nor may such definitive wording be used for the Successors or those after them when the report is weak. In every such case one must use an expression of reservation, saying: ‘It is reported from him,’ ‘It is transmitted from him,’ ‘It is related from him,’ ‘It is mentioned,’ ‘It is narrated,’ and other phrases of tentativeness, not categorical certainty.

They add that categorical formulas are reserved for reports that are ṣaḥīḥ (sound) or ḥasan (fair), whereas tentative formulas are for everything else, because a categorical statement implies the report is authentically traced to the person named. Therefore it should be used only for what is authentic; otherwise the speaker verges on lying about him.

This etiquette has been neglected by the compiler¹ and by the vast majority of jurists of our school and others—indeed, by most scholars in every discipline except the adept ḥadith specialists. Their laxity is blameworthy, for they frequently say ‘It is reported from him’ with respect to a sound ḥadith, and ‘He said’ or ‘So-and-so narrated’ with respect to a weak one—an evident departure from what is correct.”

I say: Our author—may Allah reward him well—has, along with the majority, strayed from what is correct, as will be shown in the relevant places of my commentary