2 Samuel 24:21

“And Araunah said, wherefore is my lord the king come to his servant? etc.] Which both implies admiration in him, that so great a person should visit him in his threshingfloor; that a king should come to a subject his servant, who should rather have come to him, and would upon the least intimation; it was a piece of condescension he marvelled at; and it expresses a desire to know his pleasure with him, supposing it must be something very urgent and important, that the king should come himself upon it: and to this David made answer, and David said, what he was come for: to buy the threshingfloor of thee, to build an altar to the Lord, that the plague may be stayed from the people; for though…”

“to build an altar unto the Lord, that the plague may be stayed--It is evident that the plague was not stayed till after the altar was built, and the sacrifice offered, so that what is related (Sa2 24:16) was by anticipation. Previous to the offering of this sacrifice, he had seen the destroying angel as well as offered the intercessory prayer (Sa2 24:17). This was a sacrifice of expiation; and the reason why he was allowed to offer it on Mount Moriah was partly in gracious consideration to his fear of repairing to Gibeon (Ch1 21:29-30), and partly in anticipation of the removal of the tabernacle and the erection of the temple there (Ch2 3:1).”

“24:21 so that he will stop the plague: David did not know that God had already announced the end of the plague to the angel (24:16).”

“Wherefore: Sa2 24:3, Sa2 24:18 To buy: Gen 23:8-16; Ch1 21:22; Jer 32:6-14 the plague: Sa2 21:3-14; Num 16:47-50, Num 25:8; Psa 106:30 2 Kings (2 Samuel) 24:22”