Verses with the word letteth in the Old Testament (2 verses):

2 Kings 10:24
And when they went in to offer sacrifices and burnt offerings, Jehu appointed fourscore men without, and said, If any of the men whom I have brought into your hands escape, he that letteth him go, his life shall be for the life of him.

Proverbs 17:14
The beginning of strife is as when one letteth out water: therefore leave off contention, before it be meddled with.