On the side of mount Ephraim. — Literally, on the two thighs (yarcethaim). (Comp. Psalms 128:3; Isaiah 37:24.) As to the residence of the Levite at Mount Ephraim, see Note on Judges 17:8. It is probably a fortuitous coincidence that both this Levite and Jonathan have relations with Mount Ephraim and with Bethlehem.
Took to him a concubine. — Such connections were not legally forbidden; yet it is probable that in the case of all but princes or eminent men they were looked on with moral disapprobation. She is called “a wife or concubine” — i.e., a wife with inferior rights for herself and her children.