Charles Ellicott Commentary 2 Samuel 19:32

"Now Barzillai was a very aged man, even fourscore years old: and he had provided the king with sustenance while he lay at Mahanaim; for he was a very great man." — 2 Samuel 19:32 (ASV)

Provided the king of sustenance. —An old use of the preposition “of,” meaning with. The word is the same here as that translated in the next verse feed thee, and there is a special fitness in the use of the same word in both cases which is lost in the English Version. It is translated nourish in Genesis 45:11; Genesis 47:12; Genesis 1:21, and others, and sustain in 1 Kings 17:9; Nehemiah 9:21, and others. The king proposes to return Barzillai’s service in kind, but greatly multiplied.