Niddah

R. Huna ruled: The first observed discharge of a zab conveys uncleanness  even in the case of a mishap; for it is said, This is the law of him that hath an issue, and of him from whom the flow of seed goeth out;  as 'the flow of seed' conveys uncleanness even in the case of a mishap so does the first observed discharge of a zab convey uncleanness even in the case of a mishap. Come and hear: If he observed a first discharge, he must be examined.  Is not this done to determine his  uncleanness?  — No; in regard to a sacrifice.  Come and hear: At the second observation of a discharge he must be examined.  Now for what purpose? If it be suggested: For that of a sacrifice but not for that of uncleanness  [it could be retorted:] Apply here the Scriptural text 'out of his flesh'.  which implies, but not as a result of a mishap.  Consequently it must be for the purpose of uncleanness. And since the final clause refers to an examination in regard to uncleanness must not the first clause also refer to one for uncleanness?  — What an argument! Each might refer to an examination for different purposes. Come and hear: R. Eliezer ruled: Even at the third observation he must be examined on account of the sacrifice.' From which it follows, does it not, that the first Tanna requires it  on account of the uncleanness?  — No; all may require it  on account of the sacrifice, but here they  differ on the exposition of the eth  particles. The Rabbis base no exposition on the eth particles and R. Eliezer does. 'The Rabbis base no exposition on the eth particles': 'He that hath an issue'  represents one discharge, 'his issue'  represents a second one; so far 'for the man';  while at the third discharge the All Merciful compared him to the woman.  'And R. Eliezer does': 'He that hath an issue'  represents one discharge, 'eth'  represents a second one, 'his issue'  represents a third one, while at the fourth discharge the All Merciful compared him to the woman. Come and hear: R. Isaac said, A zab, surely, was included in the same law of uncleanness as one who emitted semen,  why then was he excluded?  In order to relax the law for him in one respect and to restrict it for him in another respect. 'To relax the law for him' in that he does not become unclean in case of a mishap; and to restrict it for him'