It has to be done for a specific sin.

Salat al tawbah (Pray for Forgiveness, 2 Rakats Nafl). Does this have to have a particular intention for a specific sin? Or does this prayer cover all sins that has been committed? Also, Can this only be done once during the day or can we pray it as many times as we wants e.g. 8rakats (similar to the format of Tahajjud).

Sins |