'First born' in the Bible

And Joshua charged them at that time, saying, Cursed be the man before the LORD, that rises up and builds this city Jericho: he shall lay the foundation thereof with his firstborn, and with his youngest son shall he set up the gates of it.

There was also a lot for the tribe of Manasseh; for he was the firstborn of Joseph; for Machir the firstborn of Manasseh, the father of Gilead: because he was a man of war, therefore he was given Gilead and Bashan.