Then God promised to look after Abraham, and Abraham agreed to follow him. God told Abraham, ‘Your mob will always have to do a young man’s operation on their boys, to show that they agree with God.’ After that Abraham had a son called Isaac, and 8 days later Abraham did a young man’s operation on him. After that Isaac grew up and had a son called Jacob, and he did that operation on him too. And Jacob did the same for his 12 sons, and those 12 men became our grand-fathers of a long time ago.