Within the narrative of the story of the covenant and promise made with Avraham we learn a couple of things. One of those things is that the seed of Avraham will be gerim in a land not theirs. It's part of the story in which a covenant is established and promises are made. Another point is that Avraham and his whole household get circumcised.
At the Pesach the Pesach meal is kept within a household and all the male needed to be circumcised.
It was because HaShem remembered his covenant at the beginning of the story and the note afterwards that is was 400 and 30 years, to that day, that HaShem brought the Israelites up out from Egypt that I begane to wonder if there were any commentaries on the connection of circumcision of the Pesach with that of Avraham, if the circumcision at the Pesach was part of a commemoration to the promise and covenant made with Avraham?