But the king replied to Araunah, “No, I insist on paying you for it. I will not sacrifice to the Lord my God burnt offerings that cost me nothing.” So David bought the threshing floor and the oxen and paid fifty shekels of silver for them. 2 Samuel 24:24
“David understood the religious imperative of true sacrifice. For him, religion that cost nothing was worth nothing, either to God or humanity…
In purchasing the Land from Araunah and then utilizing it for sacrifice to the Lord, David was apparently following Torah guidelines regarding the dedication of land to the Lord (cf. Lev. 27:20-21)…
Because of David’s decisive and costly actions, “the LORD answered prayer in behalf of the land and the plague on Israel was stopped.”
In making these sacrifices for his people, David foreshadowed the actions of Jesus, the ultimate son of David, who also gave sacrificially on a hill near Jerusalem for His people so that an even more tragic plague might be stopped.”
Robert D. Bergen in 1, 2 Samuel (NAC; B & H Publishing, 1996) 480.