How 'bout this:
Rom 9:10-11a,
10 Not only that, but Rebekah's children had one and the same father, our father Isaac. 11 Yet, before the twins were born or had done anything good or bad...14 What then shall we say? Is God unjust? Not at all! 15 For he says to Moses,
"I will have mercy on whom I have mercy,
and I will have compassion on whom I have compassion."
16 It does not, therefore, depend on man's desire or effort, but on God's mercy
NIV
Hint: The "therefore" means Paul drew a conclusion from what he just got finished saying in the prior verses.
Jacob didn't achieve it even as much as he wanted it, but he did obtain it by God's mercy, as he trusting in that or he would have let go before his hip was knocked out.