Moffatt(i)
7 they are not all children of Abraham because they are descended from Abraham. No, it is through Isaac that your offspring shall be reckoned —
8 meaning that instead of God's children being the children born to him by natural descent, it is the children of the Promise who are reckoned as his true offspring.
9 For when God said, I will come about this time and Sara shall have a son, that was a word of promise.
10 And further, when Rebecca became pregnant by our father Isaac, though one man was the father of both children,
11 and though the children were still unborn and had done nothing either good or bad (to confirm the divine purpose in election which depends upon the call of God, not on anything man does),
12 she was told that the elder will serve the younger.
13 As it is written, Jacob I loved but Esau I hated.
14 Then are we to infer that there is injustice in God? Never!
15 God says to Moses, I will have mercy on whom I choose to have mercy, I will have compassion on whom I choose to have compassion.
16 You see, it is not a question of human will or effort but of the divine mercy.