Luke 2:23

In compliance with the Law of the Lord that 'every first-born male shall be dedicated to the Lord,'

Hebrews 12:23

to the festal gathering and assemblage of God's Eldest Sons whose names are enrolled in Heaven, to God the Judge of all men, to the spirits of the righteous who have attained perfection,

Treasury of Scripture Knowledge

Summary

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.

Bible References

Because

Luke 2:23
In compliance with the Law of the Lord that 'every first-born male shall be dedicated to the Lord,'
Hebrews 12:23
to the festal gathering and assemblage of God's Eldest Sons whose names are enrolled in Heaven, to God the Judge of all men, to the spirits of the righteous who have attained perfection,