Verses with the word firstborn in the Apocrypha (5 verses):

2 Esdras 6:58
But we thy people, whom thou hast called thy firstborn, thy only begotten, and thy fervent lover, are given into their hands.

Tobit 5:13
Then Tobit said, Thou art welcome, brother; be not now angry with me, because I have enquired to know thy tribe and thy family; for thou art my brother, of an honest and good stock: for I know Ananias and Jonathas, sons of that great Samaias, as we went together to Jerusalem to worship, and offered the firstborn, and the tenths of the fruits; and they were not seduced with the error of our brethren: my brother, thou art of a good stock.

Wisdom of Solomon 18:13
For whereas they would not believe any thing by reason of the enchantments; upon the destruction of the firstborn, they acknowledged this people to be the sons of God.

Sirach 17:18
Whom, being his firstborn, he nourisheth with discipline, and giving him the light of his love doth not forsake him.

Sirach 36:12
O Lord, have mercy upon the people that is called by thy name, and upon Israel, whom thou hast named thy firstborn.