1 And Satan stood up against Israel, and provoked David to number Israel. 2 And David said to Joab and to the rulers of the people, Go, number Israel from Beer-sheba even to Dan; and bring the number of them to me, that I may know it. 3 And Joab answered, The LORD make his people an hundred times so many more as they be: but, my lord the king, are they not all my lord's servants? why then doth my lord require this thing? why will he be a cause of trespass to Israel? 4 Nevertheless the king's word prevailed against Joab. Wherefore Joab departed, and went throughout all Israel, and came to Jerusalem. 5 And Joab gave the sum of the number of the people unto David. And all they of Israel were a thousand thousand and an hundred thousand men that drew sword: and Judah was four hundred threescore and ten thousand men that drew sword. 6 But Levi and Benjamin counted he not among them: for the king's word was abominable to Joab. 7 And God was displeased with this thing; therefore he smote Israel. 8 And David said unto God, I have sinned greatly, because I have done this thing: but now, I beseech thee, do away the iniquity of thy servant; for I have done very foolishly. 9 And the LORD spake unto Gad, David's seer, saying, 10 Go and tell David, saying, Thus saith the LORD, I offer thee three things: choose thee one of them, that I may do it unto thee. 11 So Gad came to David, and said unto him, Thus saith the LORD, Choose thee 12 Either three years' famine; or three months to be destroyed before thy foes, while that the sword of thine enemies overtaketh thee; or else three days the sword of the LORD, even the pestilence, in the land, and the angel of the LORD destroying throughout all the coasts of Israel. Now therefore advise thyself what word I shall bring again to him that sent me. 13 And David said unto Gad, I am in a great strait: let me fall now into the hand of the LORD; for very great are his mercies: but let me not fall into the hand of man. 14 So the LORD sent pestilence upon Israel: and there fell of Israel seventy thousand men. 15 And God sent an angel unto Jerusalem to destroy it: and as he was destroying, the LORD beheld, and he repented him of the evil, and said to the angel that destroyed, It is enough, stay now thine hand. And the angel of the LORD stood by the threshingfloor of Ornan the Jebusite. 16 And David lifted up his eyes, and saw the angel of the LORD stand between the earth and the heaven, having a drawn sword in his hand stretched out over Jerusalem. Then David and the elders of Israel, who were clothed in sackcloth, fell upon their faces. 17 And David said unto God, Is it not I that commanded the people to be numbered? even I it is that have sinned and done evil indeed; but as for these sheep, what have they done? let thine hand, I pray thee, O LORD my God, be on me, and on my father's house; but not on thy people, that they should be plagued. 18 Then the angel of the LORD commanded Gad to say to David, that David should go up, and set up an altar unto the LORD in the threshingfloor of Ornan the Jebusite. 19 And David went up at the saying of Gad, which he spake in the name of the LORD. 20 And Ornan turned back, and saw the angel; and his four sons with him hid themselves. Now Ornan was threshing wheat. 21 And as David came to Ornan, Ornan looked and saw David, and went out of the threshingfloor, and bowed himself to David with his face to the ground. 22 Then David said to Ornan, Grant me the place of this threshingfloor, that I may build an altar therein unto the LORD: thou shalt grant it me for the full price: that the plague may be stayed from the people. 23 And Ornan said unto David, Take it to thee, and let my lord the king do that which is good in his eyes: lo,I give thee the oxen also for burnt offerings, and the threshing instruments for wood, and the wheat for the meat offering; I give it all. 24 And king David said to Ornan, Nay; but I will verily buy it for the full price: for I will not take that which is thine for the LORD, nor offer burnt offerings without cost. 25 So David gave to Ornan for the place six hundred shekels of gold by weight. 26 And David built there an altar unto the LORD, and offered burnt offerings and peace offerings, and called upon the LORD; and he answered him from heaven by fire upon the altar of burnt offering. 27 And the LORD commanded the angel; and he put up his sword again into the sheath thereof. 28 At that time when David saw that the LORD had answered him in the threshingfloor of Ornan the Jebusite, then he sacrificed there. 29 For the tabernacle of the LORD, which Moses made in the wilderness, and the altar of the burnt offering, were at that season in the high place at Gibeon. 30 But David could not go before it to inquire of God: for he was afraid because of the sword of the angel of the LORD.
[AD 1781] Richard Challoner on 1 Chronicles 21:5
The difference of the numbers here and 2 Kings 24. is to be accounted for, by supposing the greater number to be that which was really found, and the lesser to be that which Joab gave in.
[AD 1781] Richard Challoner on 1 Chronicles 21:12
Three years famine: 2 Samuel 24:13 reads "seven years". The apparent discrepency lies in the error in the Hebrew manuscripts. The Greek Septuagint, which is a translation of a much more ancient version, reads "three years famine". (John Litteral) Or it can be explained as that which joined with the three foregoing years of famine mentioned, 2 Samuel 21. and the seventh year of the land's resting, would make up the seven years proposed by the prophet, 2 Samuel 24:13.
[AD 1781] Richard Challoner on 1 Chronicles 21:15
Ornan: Otherwise Areuna.
[AD 420] Jerome on 1 Chronicles 21:18
When of old the Philistines had been overcome, when their devilish audacity had been destroyed, when their champion had fallen on his face to the earth, it was from this city that there went forth a procession of jubilant souls, a harmonious choir to sing our David’s victory over tens of thousands. Here, too, it was that the angel grasped his sword, and while he laid waste the whole of the ungodly city, he marked out the temple of the Lord in the threshing floor of Ornan, king of the Jebusites. Thus early was it made plain that Christ’s church would grow up not in Israel but among the Gentiles.

[AD 735] Bede on 1 Chronicles 21:25-26
David had prepared by singing psalms, and the other prophets too by prophesying prepared for the Lord who was indeed the true Solomon a place that he might build a house, because they taught the hearts of their hearers by true faith, earnestly urging them to receive with faith and devotion the Son of God who was coming in the flesh.… It is appropriate that this place should be on the threshing floor of Ornan the Jebusite because the church is customarily designated by the term “threshing floor,” as John says of the Lord: “His winnowing fork is in his hand, and he will clear his threshing floor.” Ornan, whose name means “enlightened” and who was a Jebusite by origin, signifies the Gentiles by his origin, and by his name he indicates these same [Gentiles] who were to be enlightened by the Lord and transformed into children of the church to whom the apostle rightly says, “Once you were darkness, but now you are light in the Lord.” Jebus is the same city as Jerusalem. Now Jebus means “trampled on” but Jerusalem “the vision of peace.” As long as the Gentile Ornan reigned there it was called Jebus; but when David bought a place of burnt offering there, when Solomon built a temple to the Lord there, it was no longer called Jebus but Jerusalem, because, that is, as long as the Gentiles continued in ignorance of divine worship they were trampled on and made a mockery of by the unclean spirits, following mute idols according as they were led to do; but when they called to mind the grace of their Creator, they immediately found in themselves both the place and the name of peace, as the Lord says of them, “Blessed are the peacemakers, for they shall be called the children of God.” Therefore, while Ornan still held sway in this city it was called Jebus, but when he sold the site of his threshing floor together with his oxen and threshing sledges to king David, it took the name Jerusalem because the Gentiles who still persisted in their obstinacy were trampled on as worthless and contemptible by the wicked spirits; but when they learned to sell all they had and offer it to the true king, they could no longer be trampled on by the demons and vices but were given a greater share of inner peace, which they possessed with their Creator.

[AD 1781] Richard Challoner on 1 Chronicles 21:25
Six hundred sicles: This was the price of the whole place, on which the temple was afterwards built; but the price of the oxen was fifty sicles of silver. 2 Kings 24:24.