'Generation' in the Bible

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

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