1 Chronicles 21:22 (KJV)

And Ornan turned back, and saw the angel; and his four sons with him hid themselves. Now Ornan was threshing wheat.

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.

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.

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.

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.