Matthew Henry on 1 Chronicles 21:7-17
David is here under the rod for numbering the people, that rod of correction which drives out the foolishness that is bound up in the heart, the foolishness of pride. Let us briefly observe,
I. How he was corrected. If God's dearest children do amiss, they must expect to smart for it. 1. He is given to understand that God is displeased; and that it is no small uneasiness to so good a man as David, Ch1 21:7. God takes notice of, and is displeased with, the sins of his people; and no sin is more displeasing to him than pride of heart: nor is anything more humbling, and grieving, and mortifying to a gracious soul, than to see itself under God's displeasure. 2. He is put to his choice whether he…
Read the whole note in the consoleJamieson-Fausset-Brown on 1 Chronicles 21:9
the Lord spake unto Gad, David's seer--Although David was himself endowed with a prophetic gift, yet, in matters relating to himself or his kingdom, he was in the habit of consulting the Lord through the medium of the priests; and when he failed to do so, a prophet was sent on extraordinary occasions to admonish or chastise him. Gad, a private friend, was occasionally employed as the bearer of these prophetic messages.
Adam Clarke on 1 Chronicles 21:6
Levi and Benjamin counted he not - The rabbins give the following reason for this: Joab, seeing that this would bring down destruction upon the people, purposed to save two tribes. Should David ask, Why have you not numbered the Levites? Joab purposed to say, Because the Levites are not reckoned among the children of Israel. Should he ask, Why have you not numbered Benjamin? he would answer, Benjamin has been already sufficiently punished, on account of the treatment of the woman at Gibeah: if, therefore, this tribe were to be again punished, who would remain?
John Gill on 1 Chronicles 21:1
See Chapter Introduction
Keil & Delitzsch