What is the ruling on donating blood, given that the donor knows hospitals sell it?

Shed blood is forbidden, and it is not permissible to sell or buy it except out of necessity, because when Allah forbids something, He also forbids its price. Therefore, if someone knows that a certain entity sells blood, it is not permissible for him to donate it to them, as this would be assisting them in sin, in accordance with the Almighty's saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression."