'First born' in the Bible

And Joshua will swear in that time, saying, Cursed the man before Jehovah who shall rise up and build this city Jericho: in his first-born he shall lay its foundation and in his younger he shall set up its doors.

And there will be a bound to the tribe of Manasseh; for he was the first-born of Joseph: to Machir the firstborn of Manasseh, the father of Gilead; for he was a man of war, and there will be to him Gilead and Bashan.