And three of the thirty - The word שלשים shalishim, which we translate thirty, probably signifies an office or particular description of men. Of these shalishim we have here thirty-seven, and it can scarcely be said with propriety that we have thirty-seven out of thirty; and besides, in the parallel place, 1 Chronicles 11:11-47, there are sixteen added. The captains over Pharaoh's chariots are termed שלשים shalishim, Exodus 14:7.
The Philistines pitched in the valley of Rephaim - This is the same war which is spoken of 2 Samuel 5:17, etc.
The feat at Bethlehem by three of the thirty was the occasion of their being formed into a distinct triad; Abishai 2 Samuel 23:18, Benaiah 2 Samuel 23:20, and a third not named, were probably the three.
In the harvest time - An error for “to the rock” (compare the marginal reference).
The troop of the Philistines - The word rendered “troop” occurs in this sense only here (and, according to some, in 2 Samuel 23:11), and perhaps in Psalm 68:11. In 2 Samuel 23:16 the reading is “host” or “camp,” which may be the true reading here.
Pitched - The same Hebrew word as “encamped” in 1 Chronicles 11:15.
Valley of Rephaim - Or Giants. See 2 Samuel 21:16 note.