Yevamot

'The bridal chamber  constitutes kinyan  with ineligible women'  and Samuel said, 'The bridal chamber  does not constitute kinyan  with ineligible women'. Raba said, We also learned a similar Baraitha:  A girl who is three years of age and one day may be betrothed by cohabitation; if a levir cohabited with her, he has thereby acquired her;9   one incurs through her the guilt of intercourse with a married woman; she10  defiles her cohabitor in respect of his imparting defilement to the lower, as well as to the upper couch;  if she was married to a priest she may eat terumah, and anyone ineligible  who cohabited with her causes her ineligibility.  Thus only a girl of the age of three years and one day, who is rendered ineligible by cohabitation, is also rendered ineligible through the bridal chamber; but a girl younger than three years and one day, who is not rendered ineligible by cohabitation, is not rendered ineligible through the bridal chamber either.  This proves it. Rami b. Hama stated: [In regard to the question whether] the bridal chamber  constitutes kinyan  with ineligible women,  we arrive at a difference of opinion between R. Meir and R. Eleazar and R. Simeon.