Prayer: Doubting the Source of Blood When Wounded
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 839
If there is a wound on one’s body, and on his body or clothing, he sees blood that is equal to or more than the area covered by a dirham but does not know whether it is blood from the wound or not, the obligatory precaution is that he must not perform prayers with it.