Albert Barnes Commentary 1 Kings 18:5

"And Ahab said unto Obadiah, Go through the land, unto all the fountains of water, and unto all the brooks: peradventure we may find grass and save the horses and mules alive, that we lose not all the beasts." — 1 Kings 18:5 (ASV)

To all fountains of water and to all brooks - Rather, “to all springs of water and to all torrent-courses.” The former are the perennial streams; the latter are the torrent-courses which become dry in an ordinary summer.

All the beasts - Rather, some, or, “a portion of our beasts.”