giving blood
Leviticus Chapter 17:14
For it is the life of all flesh; the blood of it is for the life thereof: therefore I said unto the children of Israel, Ye shall eat the blood of no manner of flesh: for the life of all flesh is the blood thereof: whosoever eateth it shall be cut off.
John Chapter 15:13
Greater love hath no man than this, that a man lay down his life for his friends.