'Seventy' in the Bible

Now Ahab had seventy sons in Samaria. And Jehu wrote letters and sent them to Samaria, to the rulers of Jezreel, the elders, and to the guardians of the children of Ahab, saying,

Then he wrote a letter to them a second time saying, “If you are on my side, and you will listen to my voice, take the heads of the men, your master’s sons, and come to me at Jezreel tomorrow about this time.” Now the king’s sons, seventy persons, were with the great men of the city, who were rearing them.

When the letter came to them, they took the king’s sons and slaughtered them, seventy persons, and put their heads in baskets, and sent them to him at Jezreel.