Romans 9:7-9

WNT(i) 7 nor because they are Abraham's true children. But the promise was "THROUGH ISAAC SHALL YOUR POSTERITY BE RECKONED." 8 In other words, it is not the children by natural descent who count as God's children, but the children made such by the promise are regarded as Abraham's posterity. 9 For the words are the language of promise and run thus, "ABOUT THIS TIME NEXT YEAR I WILL COME, AND SARAH SHALL HAVE A SON."