28 But we, brothers, like Isaac, are children of promise.
Galatians 4:28 Cross References - CAB
Acts 3:25
25 You are sons of the prophets, and of the covenant which God made with our fathers, saying to Abraham, 'And in your offspring all the families of the earth shall be blessed.'
Romans 4:13-18
13 For the promise that he should be heir of the world was not to Abraham or to his seed through the law, but through the righteousness of faith.
14 For if those who are of the law are heirs, faith is made void and the promise has been nullified,
15 because the law produces wrath; for where there is no law neither is there transgression.
16 Therefore it is of faith that it may be according to grace, so that the promise might be sure to all the seed, not only to those of the law, but also to those of the faith of Abraham, who is the father of us all,
17 (just as it is written, "I have appointed you a father of many nations") before God, whom he believed, the One who gives life to the dead and calls those things which are not as though they were;
18 who, contrary to hope, on hope believed, so that he should become a father of many nations, according to what was spoken, "So shall your descendants be."
Romans 9:8-9
Galatians 3:29
29 And if you are Christ's, then you are Abraham's seed, and heirs according to the promise.
Galatians 4:23
23 But he who was of the servant girl was born according to the flesh, and he of the free woman through the promise,