Deuteronomy 29:13-15

so that He may establish you today as His people and that He may be your God, just as He spoke to you and as He swore to your fathers, to Abraham, Isaac, and Jacob. “It is not with you alone that I am making this covenant and this oath, but with those [future Israelites] who are not here with us today, as well as with those who stand here with us today in the presence of the LORD our God