Flowing blood is forbidden.

The second place in the list of forbidden things is the flowing blood. Hazrat Ibn Abbas. It was asked, what is the Shari'ah ruling on spleen? He said: You can eat. People said, is it really just blood clots? He replied, "Allah has forbidden only flowing blood." Because it is unclean, dirty, filthy. Clean and pure and healthy human nature cannot help but hate it. Moreover, like dead animals, it is very possible to contain harmful germs.

 

In the age of ignorance, if someone felt intense hunger, he would put a bone or any sharp object in the mouth of a camel or other animal. He eagerly drank the blood that flowed out of it. As a result of this kind of work, the animals were forced to suffer traumatic pain. As the blood flowed out, it became inevitable that it would weaken. For all these reasons, Allah has forbidden flowing blood.