Related על קידושין 4:8

(Translated from Ehrfurt manuscript:) A man who said: "My son is a mamzer", "My son is the son of a divorcee" or "the son of a halutzah (a woman whose levirate bond was broken with halitzah)", if [he said this] about a minor—he is believed; but about a major—he is not believed—words of Rabbi Yose. But Hakhamim say: Even if both of them (the man and woman) say that the foetus in her womb is a mamzer—they is not believed.