Roma 4:13

4:13 For the promise ¹  to Abraham or to his descendants that he would inherit the world was not fulfilled through the law, but through the righteousness that comes by faith.

Roma 4:16

4:16 For this reason it is by faith so that it may be by grace, ²  with the result that the promise may be certain to all the descendants – not only to those who are under the law, but also to those who have the faith of Abraham, ³  who is the father of us all

[4:13]  ¹ sn Although a singular noun, the promise is collective and does not refer only to Gen 12:7, but as D. Moo (Romans 1-8 [WEC], 279) points out, refers to multiple aspects of the promise to Abraham: multiplied descendants (Gen 12:2), possession of the land (Gen 13:15-17), and his becoming the vehicle of blessing to all people (Gen 12:13).

[4:16]  ² tn Grk “that it might be according to grace.”

[4:16]  ³ tn Grk “those who are of the faith of Abraham.”