1 Samuel 30:23-25

23But David said, “My brothers, you must not do this with what the Lord has given us. He protected us and handed over to us the raiders who came against us.

24Who can agree to your proposal? The share of the one who goes into battle is to be the same as the share of the one who remains with the supplies. They will share equally.”

25And it has been so from that day forward. David established this policy as a law and an ordinance for Israel and it still continues today.