Jamieson, Fausset and Brown on 1 Samuel 30:21

21. David came to the two hundred men, which were so faint that they could not follow--This unexpected accession of spoil was nearly proving an occasion of quarrel through the selfish cupidity of some of his followers, and serious consequences might have ensued had they not been prevented by the prudence of the leader, who enacted it as a standing ordinance--the equitable rule--that all the soldiers should share alike (see Nu 31:11; see on Nu 31:25).