Numbers 3:13

Because all the firstborn [are] mine; [for] on the day that I smote all the firstborn in the land of Egypt I hallowed unto me all the firstborn in Israel, both man and beast: mine shall they be: I [am] the LORD.

Ver. 13. Because all the firstborn.] So they were from the beginning: but here is noted a continuance of this ordinance, when it is said that he sanctified the first born to himself, what time he smote every firstborn in Egypt. Now the firstborn are said to be God's by a singular right, Exo 13:2 and so they were types, (1.) Of Christ, Rom 8:29 to whom therefore we must give the honour of his first birthright; all our sheaves must vail and bow to his sheaf: (2.) Of Christians; those "firstborn whose names are written in heaven," Heb 12:23 who are dear to God, as his firstborn, Exo 4:22 and so "higher than the kings of the earth," Psa 89:27 for they are "kings and priests unto God," Rev 1:6 to "serve him day and night in his temple." Rev 7:15