5 and Abraham is a son of a hundred years when he births his son Yischaq.
Genesis 21:5 Cross References - ECB
Genesis 17:1
1 And so be it, Abram is a son of ninety years and nine years and Yah Veh is seen by Abram and says to him, I am El Shadday; walk at my face and be integrious:
Genesis 17:17
17 Then Abraham falls on his face and laughs and says in his heart, Birth - a son of a hundred years? And Sarah, a daughter of ninety years, birth?
Romans 4:19
19 And not being frail in the trust, he neither considered his own body - already necreotized - being some hundred years old, nor yet the necrosis of the matrix of Sarah: