Kommentar zu Schemuel I 30:25

From that day on. [Literally 'from that day and above']. It is not stated: "[from that day] on" but "[from that day] and above [=before]." Avrohom had already instituted this statute [when he said,] "Only what the lads have eaten,"⁵Bereishis 14:24, where it is stated that Avrohom distributed shares of the spoils of war to those who stayed behind and guarded the equipment. those are the ones who stayed with the equipment, "and the portion of the men"⁶Ibid. who went to war. In Breishis Raboh.