'An Israelite girl married to a priest, a priestly girl married to an Israelite - and she produced a daughter with him, and the daughter went and married a slave or a gentile and produced a son from him - lo, this son is a mamzer.' (Yebamot 7:5, clause III)
Then:
'Mamzerim ... are prohibited [from entering the congregation of the L-rd], and the prohibition concerning them is forever, all the same being males and females.' (Yebamot 8: 3 clause III)