Cross reference
Genesis 17:27
27 And all the men of his house, those born in the house, and those bought with money of a foreigner, were circumcised with him.
Genesis 18:19
19 For I have known him, to the end that he may command his children and his household after him, that they may keep the way of Jehovah, to do righteousness and justice; to the end that Jehovah may bring upon Abraham that which he hath spoken of him.