What is the ruling on nosebleeds during prayer?

Question:
Does blood flowing from the nose during prayer invalidate the prayer or not?

Answer:
A nosebleed—which is blood flowing from the nose—if it is slight, the truth that is beyond doubt is that it does not invalidate the ablution, nor does it invalidate the prayer, and what it causes on the garment is excused if it is slight.
As for if it is heavy, the scholars differed regarding it: some said that one should plug his nose, and the prayer is not invalidated. Others said that rather, the prayer is invalidated due to its heaviness, and he must break off the prayer, wash his nose, and strive to get rid of this blood, then resume the prayer. This is the most cautious and preferable position; this opinion is the most cautious and preferable because of the care it takes for the prayer, because it avoids the disagreement, and because blood is ritually impure, and only the slight amount is excused.
So this is the most cautious course for the believer if he is afflicted with a heavy nosebleed: he breaks off the prayer and places something on his nose to contain the blood so that it does not defile his garments, and so that it does not defile the mosque. Then he attends to what has flowed out, and after it stops, he performs ablution and repeats the prayer. This is the most cautious and strongest of the scholars' opinions; because of the care it takes for the religion, and because it keeps away from the causes of danger to this great act of worship.