Albert Barnes Commentary 1 Samuel 22:3

"And David went thence to Mizpeh of Moab: and he said unto the king of Moab, Let my father and my mother, I pray thee, come forth, [and be] with you, till I know what God will do for me." — 1 Samuel 22:3 (ASV)

Mizpeh of Moab - A reasonable conjecture connects it with “Zophim” (a word from the same root as Mizpeh) on the top of Pisgah (Numbers 23:14). It is probable that David’s descent from Ruth the Moabitess had something to do with his seeking asylum for Jesse, her grandson, in the land of her birth. It would have been very easy to get to the Jordan River from the vicinity of Bethlehem and cross over near where it empties into the Dead Sea.

Come forth, and be with you - The construction of the Hebrew is very strange. The Vulgate, Syriac, and Arabic seem to have read “dwell” instead of “come forth.”