'Never Fail' in the Bible

Now, O Lord, God of Israel, keep the promise you made to your servant, my father David, when you said, 'You will never fail to have a successor ruling before me on the throne of Israel, provided that your descendants watch their step and serve me as you have done.'

Now, O Lord God of Israel, keep the promise you made to your servant, my father David, when you said, 'You will never fail to have a successor ruling before me on the throne of Israel, provided that your descendants watch their step and obey my law as you have done.'