'Never Fail' in the Bible

For thus saith Jehovah: There shall never fail to David a man to sit upon the throne of the house of Israel;

The Levitical priests will never fail to have a man always before Me to offer burnt offerings, to burn grain offerings, and to make sacrifices.”

Then may my covenant also be broken, which I made with David my servant, and so he not to have a son to reign in his Throne. So shall also the priests and Levites never fail, but serve me.

therefore thus says the Lord of hosts, the God of Israel, “Jonadab the son of Rechab shall never fail to have a man (descendant) to stand before Me always.”’”