2 Chronicles 14

Asa prayed, and his prayer manifested great power: when Zerah the Indian [Ethiopian] went out against him with an army of one million with him, Asa then prayed, saying, "By this shall your power be known, O our God, when you finish off a vast people by means of a small people." God heard his prayer and sent his angel to rout them. Thus the vast army was defeated by the power of Asa's prayer.