:wasalamex
This might be of help:
Imaam Nawawi (rahimullaah) said in Kitaab-ul-Adhkaar:
"The ulama among the experts in hadeeth and the experts in law and others have said: it is permissible and (also) recommended that the religious practice concerning good deeds and good character, encouragement to good and discouragement from evil be based (even) on weak hadith as long as it is not forged (maudu).
As for ahkaam (legal rulings) such as what is permitted and what is forbidden, or the modalities of trade, marriage, divorce and other than that: one's practice is not based upon anything other than saheeh or hasan hadeeth, except as a precaution in some matter related to one of the above, for example, if a weak hadeeth was cited about the reprehensibility of certain kinds of sales or marriages. In such cases what is recommended is to avoid such sales and marriages, but it is not obligatory."
However, Sheikh-ul Islaam, Ibn Taymiya (rahimullaah) and Abu Al-Arabi Al-Maliki (rahimullaah) were of the opinion that you could not use weak narrations full stop. There are other scholars who adhered to this opinion. On the other hand there were other scholars who agreed with Imaam Nawawi (rahimullaah) such as Ibn Hajar Asqalani,Al-Khateeb Al-Baghdadi and generally the Hanafi school of thought.
Allaahu'3llaam.