'Fourth Generation' in the Bible

And LORD said to Jehu, Because thou have done well in executing that which is right in my eyes, [and] have done to the house of Ahab according to all that was in my heart, thy sons of the fourth generation shall sit on the throne o

This was the word of LORD which he spoke to Jehu, saying, Thy sons to the fourth generation shall sit upon the throne of Israel. And so it came to pass.