2 Kings 3:26

People imitate those who do good deeds, therefore, not out of love for these good deeds but because of their usefulness. For Balaam also flattered [God], in that he had seven altars built because he had heard concerning these ancient ones that, with regard to the sacrifices they had offered to him, their prayers were accepted. The king of Moab took note of Jephthah. But, because it was his firstborn and a human being rather than an animal that he killed, God took pity on him, since it was in affliction that he did it and not through love. In the case of Jephthah, if it had been one of his servants who had been first to encounter him, he would have killed him. But, in order that people would not engage in the sacrifice of their fellow human beings, he caused his own daughter to meet him, so that others would be afraid, lest they offer human beings by vow to God.

Therefore Mesha, who had lost all his hope in his armies, made an about-face to ask the gods for help, because he had seen that no human being could help him. Certain wise men of his country said to him that it was necessary to implore the mercy of the God of Israel by means of an extraordinary sacrifice, for exactly the same reason which Abraham, the father of the Israelites, had made his offering, which had been quite pleasing to God, according to the tradition that is generally renowned among the Canaanites. But the power and the strength of God had already been recognized by all with great admiration for what he had done before all the Moabites. Indeed, no one but him had made the water flow on his people in the desert of Edom, and they had never heard of or known another God who granted his worshipers greater benefits. Therefore the king, who could not deny the miracle that he had seen with his own eyes, did not want to be deprived of sufficient aid in the difficulties that encircled him. He was confirmed [in his hope] and abandoned the worship of idols by taking refuge in the powerful God who had created a new sea in the desert. Therefore he was invited by the word of the wise men and nobles of Moab to make a great sacrifice and to offer his firstborn child, the pillar of his house and the hope of his kingdom, on the city walls, before the armies that besieged him. He wanted the Hebrew to see the sacrifice he was about to make to the God of Abraham according to the teaching of Abraham.And then the wrath against the Israelites increased, because the calamities, which the Scripture accurately relates after these events, happened to them again. They had seen how God protected them, and the abundance of water that he had made miraculously flow for them and the retreat of their enemies before them. Nevertheless, they persisted in their dishonor, and their hearts were still attached to their calf.