Commentary for Bava Batra 120:2

...we should decree upon ourselves not to marry a woman: It is a wonder, as it is written, "be fruitful and multiply." And perhaps it is only referring to those who already fulfilled "be fruitful and multiply" [by having a son and a daughter]. And that the "descendants of Abraham will cease," is that they only give birth to a son and a daughter.

In a good way, and not through the gentiles, and the commandments will no longer be negated.