Deuteronomy 10:16 in the World English Bible
Circumcise therefore the foreskin of your heart, and be no more stiff-necked.
Context
15 Only the LORD had a delight in thy fathers to love them, and he chose their seed after them, even you above all people, as it is this day.
16 Circumcise therefore the foreskin of your heart, and be no more stiffnecked.
17 For the LORD your God is God of gods, and Lord of lords, a great God, a mighty, and a terrible, which regardeth not persons, nor taketh reward: