'Fail' in the Bible

Thy sons and thy daughters shall be given unto another people, and thine eyes shall look, and fail with longing for them all the day long: and there shall be no might in thine hand.

Be strong and of a good courage, fear not, nor be afraid of them: for the LORD thy God, he it is that doth go with thee; he will not fail thee, nor forsake thee.

And the LORD, he it is that doth go before thee; he will be with thee, he will not fail thee, neither forsake thee: fear not, neither be dismayed.