In the 2nd book of Chronicles chapter 25, Amaziah (king of Judah) was about to face a formidable enemy. While he had rounded up a decent army, Amaziah felt he needed more power and so he hired men from Israel for a hundred talents of silver (about 3 3/4 tons).
But this is what happened next:
"But a man of God came to him and said - O king, these troops from Israel must not march with you, for the Lord is not with Israel ... not with any of the people of Ephraim. Even if you go and fight courageously in battle, God will overthrow you before the enemy, for God has the power to help or to overthrow."