Verses for fail not

Take heed now that ye fail not to do this: why should damage grow to the hurt of the kings?

And the LORD shall guide thee continually, and satisfy thy soul in drought, and make fat thy bones: and thou shalt be like a watered garden, and like a spring of water, whose waters fail not.

It is of the LORD's mercies that we are not consumed, because his compassions fail not.

But I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren.