TSK · Judges 8:35

He went to his father's house at Ophrah, and killed his brothers the sons of Jerubbaal, being seventy persons, on one stone: but Jotham the youngest son of Jerubbaal was left; for he hid himself.

Thus Joash the king didn't remember the kindness which Jehoiada his father had done to him, but killed his son. When he died, he said, "May Yahweh look at it, and repay it."