Salam I went for a blood test today. When the phlebotomist withdrew the needle, a single drop of blood gushed out, which I dried with a piece of cotton. Later on, I forgot to clean my arm and when the time for namaz started, I did wuzu and prayed. Afterwards, I remembered that I had to clean my arm first. My question is that should I consider my arm najis? I read somewhere that if the quantity of blood is less than the area of a nail, then it is paak. What is the exact rule for this? Thanks.