Niddah

Both Rab and Samuel laid down: The halachah is that  one performs the obligatory marital act and withdraws forthwith. R. Hisda raised an objection: It once happened that Rabbi allowed a woman intercourse on four nights in twelve months!  — Said Rabbah  to him: What need have you  for repeating the same objection? Rather raise one from our Mishnah?  — But he was of the opinion that a practical decision  is weightier.  At all events,  does not a difficulty arise against Rab and Samuel?  They acted in agreement with our Masters; for it was taught: Our Masters decided by a second count of votes  that one only performs the obligatory marital act and withdraws forthwith. 'Ulla stated: When R. Johanan and Resh Lakish were engaged in the discussions of the chapter on the 'Young Girl'  they carried away from it only what a fox carries away from a ploughed field,  and concluded it  with this statement: One performs the obligatory marital act and withdraws forthwith. Said R. Abba to R. Ashi: Now then,  should a scrupulous man  not even finish his act? — The other replied: If that were to be the rule  one would be ill at ease  and would withdraw altogether. Our Rabbis taught: But all these women if they  were continually discharging blood during  the four nights and after the four nights or  during the night and after it, must without exception  examine themselves;  and in the case of all these R. Meir imposes restrictions in agreement with the view of Beth Shammai.  In regard, however, to other observations of blood,  concerning which a difference of opinion exists between Beth Shammai  and Beth Hillel,  he is guided  by the colour of the blood; for R. Meir ruled: The colours of the various kinds of blood are different from one another. In what manner? Menstrual blood is red, the blood of virginity is not so red; menstrual blood is turbid, the blood of virginity is not turbid; menstrual blood issues from the source, the blood of virginity issues from the sides. R. Isaac son of R. Jose citing R. Johanan stated: This is the ruling of R. Meir alone, but the Sages maintain: All the colours of the various kinds of blood are the same. Our Rabbis taught: A woman who observes a discharge of blood  as a result of marital intercourse may perform her marital duty the first, second and third time. Henceforward,  however, she may not perform it until she is divorced