1 Samuel 30:23-25

23But David said, “My brothers, don’t do that with the things which the Lord has given us. He has protected us and handed the troops that attacked us over to us.

24Besides, who is going to pay attention to what you have to say in this matter? Certainly, the share of those who go into battle must be like the share of those who stay with the supplies. They will all share alike.”

25From that time on he made this a rule and a custom in Israel as it is to this day.