R. Nathan says: Whence is it derived that "ben ha'arbayim" signifies midday? Even though there is no proof for this, it is intimated in (Jeremiah 6:4) "Prepare for battle against her. Arise and let us go up at noon (midday). Woe unto us for the day is declining, for the shadows of evening go forth!"
Rabbi Nathan Takes on a Question That Had Puzzled Scholars
Mekhilta Tractate Pischa 5:22