Is it permissible to pray with small specks of blood on clothes due to back pimples?

Blood is impure (najis). If it is abundant, prayer with it is invalid. If it is little, there is a difference of opinion among scholars regarding its pardonability. Most scholars consider a small amount of blood and pus to be pardonable. Among those from whom this was narrated are Ibn Abbas, Abu Hurairah, and others. The apparent position of the Hanbali school (madhhab Ahmad) is that "little" is what does not become excessive in one's heart, and this is the saying of Ibn Abbas.