Charles Ellicott Commentary Genesis 31:49

"and Mizpah, for he said, Jehovah watch between me and thee, when we are absent one from another." — Genesis 31:49 (ASV)

Mizpah. —That is, Watchtower. There is, probably, a play on words in this name concerning the pillar which Laban proceeds to set up, and which in Hebrew is Mazebah.

In the reason given for the name, Laban calls Jacob’s God Jehovah, an appellation which he must have learned from Jacob, and which proves not merely that he had some knowledge of Hebrew but that he and Jacob had talked together about religious subjects, and that he was not a mere idolater, though he did call the teraphim his gods.