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 14:23

14:23 But the man who doubts is condemned if he eats, because he does not do so from faith, and whatever is not from faith is sin. ² 

[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).

[14:23]  ² tc Some mss insert 16:25-27 at this point. See the tc note at 16:25 for more information.