Yevamot

[The law, surely,] concerning all the others also was arrived at  by exposition!  — Granted that in respect of [exemption from] the levirate marriage [the law in relation to them] was arrived at by exposition, the principle of prohibition [of sexual intercourse] with them has been explicitly enunciated in Scripture, [while as regards] his daughter  the very principle underlying the prohibition [of intercourse with her] has been arrived at by exposition; for Raba  stated: R. Isaac b. Abdimi told me, 'Hennah  is derived from hennah  and zimmah  is derived from zimmah'. Now that it has been stated that preference is given to whatever is arrived at by exposition, the Tanna should have placed  HIS WIFE'S SISTER last!  — As he was dealing with a prohibition due to sisterhood  he mentioned also HIS WIFE'S SISTER. Then let him relegate  the entire passage  to the end!  — But [this is really the explanation]: The Tanna follows the order of the respective degrees of kinship. He, therefore, mentions [first] HIS DAUGHTER, THE DAUGHTER OF HIS DAUGHTER AND THE DAUGHTER OF HIS SON because they are his own next of kin; and since he enumerated three generations of his relatives in descending order he enumerated also three generations of her  relatives in descending order. Having enumerated three generations of her  relatives in descending order he proceeded to enumerate also three generations of her relatives in ascending order. He then mentions HIS SISTER and HIS MOTHER'S SISTER who are his blood  relatives;  and while dealing with prohibitions due to brotherhood he also mentions HIS WIFE'S SISTER. And it would indeed have been proper that HIS DAUGHTER-IN-LAW should be placed before THE WIFE OF HIS BROTHER WHO WAS NOT HIS CONTEMPORARY, since it is not on account of kinship  that the latter is forbidden, but as he was dealing with a prohibition due to brotherhood he mentioned also THE WIFE OF HIS BROTHER WHO WAS NOT HIS CONTEMPORARY and then mentioned HIS DAUGHTER-IN-LAW. What argument can be advanced for using  the expression EXEMPT  and not that of  'prohibit'?  — If 'prohibit' had been used it might have been assumed that the levirate marriage only was forbidden but that halizah  must nevertheless be performed,  hence it was taught  [that halizah also need not be performed]. Let it then be stated,  'She is forbidden to perform halizah!  — No harm, surely, is thereby done.  But why indeed should not [the expression of prohibition be applicable to halizah]? If you were to say that halizah is permissible, [one might say that] levirate marriage is also permitted!  — As a rival  is forbidden only where the commandment [of the levirate marriage] is applicable but is permitted where the commandment is not applicable,  it was therefore necessary to use the expression, EXEMPT. What justification is there for stating, FROM THE HALIZAH AND FROM THE LEVIRATE MARRIAGE when it would have been sufficient to state  FROM THE LEVIRATE MARRIAGE only?  — If FROM THE LEVIRATE MARRIAGE only had been stated it might have been assumed that she must perform halizah  though she is exempt from the levirate marriage, hence it was taught  that whoever is subject  to the obligation of levirate marriage is also subject to halizah and whosoever is not subject to the obligation of the levirate marriage is not subject to halizah. Let it [first] be stated,  FROM THE LEVIRATE MARRIAGE [and then] FROM THE HALIZAH,  or else only FROM THE HALIZAH?  — This Mishnah represents the view of Abba Saul who maintains that the commandment of halizah takes precedence over that of levirate marriage. What [was intended] to be excluded [by the] numeral at the beginning  and what [again was intended] to be excluded [by the] numeral at the end?