II Kings 10:6-7

Then he wrote a second letter to them, saying: If you are for me and will obey my voice, take the heads of the men, your master’s sons, and come to me at Jezreel by this time tomorrow. Now the king’s sons, seventy persons, were with the great men of the city, who were rearing them. So it was, when the letter came to them, that they took the king’s sons and slaughtered seventy persons, put their heads in baskets and sent them to him at Jezreel.