'Fourth Generation' in the Bible

And the LORD said to Jehu, Because thou hast done well in executing that which is right in my eyes, and hast done to the house of Ahab according to all that was in my heart, thy children of the fourth generation shall sit on the throne of Israel.

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