Charles Ellicott Commentary 1 Kings 18:42

"So Ahab went up to eat and to drink. And Elijah went up to the top of Carmel; and he bowed himself down upon the earth, and put his face between his knees." — 1 Kings 18:42 (ASV)

Put his face between his knees.—The attitude is, of course, one of prayer, but is a peculiar attitude—distinct from the ordinary postures of standing and kneeling—which has been noted as still existing among modern dervishes. Possibly it is characteristic of the vehement excitement of the moment, and of the impulsive nature of Elijah.