Of my bone - Render as in preceding verse, “art thou not my bone and my flesh?” It is curious to note how the phrase is used in 2 Samuel 5:1 of common descent from Israel, in 2 Samuel 19:12 of the closer kindred of the tribe of Judah, and in this verse of the yet nearer kindred between David and Amasa his sister‘s son.
Captain in the room of Joab - It is very plain that David felt the weight of Joab‘s overbearing influence to be very oppressive (compare 2 Samuel 19:22; 2 Samuel 3:39; 2 Samuel 16:10). He was, at this time, very angry with Joab for killing Absalom; and so, thinking it of vital importance to win over Amasa and the army of Judah, he did not scruple to offer him Joab‘s high post.