Matthew Poole and continuators on Genesis 46:1

1 AND Israel took his journey with all that he had, and came to Beersheba, and offered sacrifices unto the God of his father Isaac .

Both in thankfulness to God for former favours, and especially for Iosephs preservation and happiness; and by way of supplication to God for his direction in this great case, whether he might leave the promised land of Canaan and go into the idolatrous and impious land of Egypt; and for his protection and blessing as well in his journey as in Egypt.

Whom Isaac honoured and served, and who had constantly protected and provided for Isaac and confirmed his covenant with him. He mentions Isaac rather than Abraham, partly for Isaacs honour, to shew that though Isaac was much inferiour to Abraham in gifts and graces, yet God was no less Isaacs than Abrahams God, and therefore would be his God also notwithstanding his unworthiness: and partly for his own comfort, because Isaac was Iacobs immediate Parent and had transferred the blessing of the Covenant from Esau to Iacob, and the validity of that translation depended upon Isaacs interest in God.