John Gill Commentary Genesis 17:7

"And I will establish my covenant between me and thee and thy seed after thee throughout their generations for an everlasting covenant, to be a God unto thee and to thy seed after thee." — Genesis 17:7 (ASV)

And I will establish my covenant between me and you
Not only renew it, but confirm it by the following token of circumcision:

and your seed after you, in their generation ;
such blessings in it as belonged to his natural seed, as such he confirmed to them, to be enjoyed by them in successive ages; and such as belonged to his spiritual seed, to them also, as they should be raised up in future times in one place and another:

for an everlasting covenant ;
to his natural seed, as long as they should continue in the true worship of God; and in their own land; or until the Messiah came, in whom the covenant of circumcision had its accomplishment, and was at an end; and to all his spiritual seed, with respect to the spiritual blessings of it, which are everlasting, and are never taken away, or become void;

to be a God unto you, and to your seed after you ;
to his natural seed, as the God of nature and providence, communicating the good things of life unto them; protecting, preserving, and continuing them in the land he gave them, and in the possessive of all the good things in it, so long as they were obedient to him as their King and their God; and to his spiritual seed, as the God of all grace, supplying them with grace here, and bestowing upon them glory hereafter.