Exodus 25:18-20 (KJV):

18And thou shalt make two cherubims of gold, of beaten work shalt thou make them, in the two ends of the mercy seat. 19And make one cherub on the one end, and the other cherub on the other end: even of the mercy seat shall ye make the cherubims on the two ends thereof. 20And the cherubims shall stretch forth their wings on high, covering the mercy seat with their wings, and their faces shall look one to another; toward the mercy seat shall the faces of the cherubims be.