The World Federation One Stop Fiqh

Ruling 843

If blood spills on clothing that has a lining and reaches the lining, or it spills on the lining and reaches the upper layer of the clothing, or from one piece of clothing it reaches another piece, in each of these cases, the blood must be considered to be separate. Therefore, if the combined area of blood is less than a dirham, the prayers are valid; otherwise, they are invalid unless the areas are joined together such that they would be commonly considered to be one area of blood, in which case if the area of blood on the side that has spread more is less than a dirham, prayers with it are valid; but if it is the size of a dirham or more, then prayers performed with it are invalid.