John Calvin Commentary Genesis 17:10

"This is my covenant, which ye shall keep, between me and you and thy seed after thee: every male among you shall be circumcised." — Genesis 17:10 (ASV)

Every man-child among you shall be circumcised. Although God promised to both males and females what he later sanctioned by circumcision, he nevertheless consecrated, in one sex, the whole people to himself. For since, by this symbol, the promise which was given indiscriminately to males and females is confirmed, and since it is certain that females as well as males needed confirmation, it is therefore evident that the symbol was ordained for the sake of both sexes.

Nor is it a valid objection to this reasoning to say that each individual is commanded to participate in the sacraments if they are to derive any benefit from them, on the basis that no benefit is received by those who neglect their use. For the covenant of God was engraved on the bodies of the males with this condition attached: that females, as their associates, should also be partakers of the same sign.