When the king of Ai saw. Literally, “according to the seeing of the king of Ai,” that is, immediately upon his seeing or knowing. The word sometimes takes on this latter sense. Probably the guards were the first to discover Joshua and his troops and to report them to the king. A leader is often given credit for that which is done by those under him. Immediately he wakens his officers and men, and together they rush out to meet Israel, perhaps in hope of another easy victory.
At a time appointed. Hebrew lammo‘ed. The LXX here reads, “straight out,” and the Syriac, “in the valley.” By reading mored for mo‘ed we get the translation “to the descent” (see on chapters 7:2, 5; 8:13).
Before the plain. Literally, “in the sight of the Arabah.” The Hebrew ‘arabah means, “a waste region,” “a desert.” With the article it refers specifically to the valley, or plain, of Jordan. Israel’s flight probably took them toward Gilgal.