'Certainly' in the Bible

David inquired of Yahweh, saying, "Shall I go up against the Philistines? Will you deliver them into my hand?" Yahweh said to David, "Go up; for I will certainly deliver the Philistines into your hand."

Most certainly my house is not so with God, yet he has made with me an everlasting covenant, ordered in all things, and sure, for it is all my salvation, and all [my] desire, although he doesn't make it grow.

The king said to Araunah, "No; but I will most certainly buy it from you for a price. I will not offer burnt offerings to Yahweh my God which cost me nothing." So David bought the threshing floor and the oxen for fifty shekels of silver.