Whoever declares others to be genealogically unfit is himself
genealogically unfit, never speaks in praise of others, and declares
them unfit w
ith his own blemish.
A
certain man in Pumbedita offended Rav Yehuda. The man used to call
other people slaves. Rav Yehuda excommunicated him and pronounced him a
slave. In the court of Rav Nachman Rav Yehudah explained that he
pronounced the man slave because he called others slaves. Normally,
this only allows one to suspect, but on that day Rav Matna, who had not
visited Pumbedita for 13 years, came and confirmed that the man was a
slave, and more blemishes were discovered.