1 Samuel 30:21-25

When David came to the two hundred men who were too exhausted to follow David and had been left behind at the brook Besor, and they went out to meet David and to meet the people who were with him, then David approached the people and greeted them.

Then all the wicked and worthless men among those who went with David said, “Since they did not go with us, we will not give them any of the spoils that we have recovered, except to every man his wife and his children, so that they may lead them away and leave.”

But David said, “You must not do so, my brothers, with what the Lord has given us, for He has protected us and handed over to us the band of raiders that came against us.

And who will listen to you in this matter? For as is the share of the one who goes down into the battle, so shall be the share of the one who stays by the baggage; they shall share alike.”

So it has been from that day forward, that he made it a statute and an ordinance for Israel to this day.