Yevamot

and [in connection with this] R. Abbahu stated that deduction is made  by a comparison between the two expressions of 'pursuit':  Here it is written, Seek peace and pursue it and elsewhere it is written, He that pursueth  after righteousness and mercy findeth life, prosperity and honour. 'The annulment of vows', in accordance with [a statement of] R. Nathan. For it was taught: R. Nathan said, 'If a man makes a vow it is as if he has built a high place  and if he fulfils it,  it is as if he has offered up a sacrifice upon it'. 'And keep away from three things: From mi'un', since it is possible that when she becomes of age she will change her mind. 'From [receiving] deposits' [applies to deposits made by] his fellow townsman who [regards] his house as his own house. 'From acting as surety [refers to would-be] sureties in Shalzion.  For R. Isaac said, 'What was meant by the Scriptural text, He that is surety for a stranger shall smart for it?  Evil after evil  comes upon those who receive proselytes,  and upon the sureties  of Shalzion and upon him who rivets  himself to the word of the halachah. That 'those who receive proselytes', [bring evil upon themselves, is deduced] in accordance with [a statement of] R. Helbo. For R. Helbo stated: Proselytes are hurtful to Israel as a sore on the skin. 'The sureties of Shalzion [bring evil upon themselves]' because [in that place] they practice 'pull out and thrust in'. 'Who rivets himself to the word of the halachah', [brings evil upon himself], for it was taught: R. Jose said, 'Whosoever says that he has no [desire to study the] Torah, has no [reward for the study of the] Torah'. Is not this obvious? — But [this must be the meaning]: 'Whosoever says that he has only [an interest in the study of the] Torah  has only [reward for the study of the] Torah'. This, however, is also obvious! — But [the meaning really is] that he has no [reward] even [for the study of the] Torah. What is the reason? — R. Papa replied: Scripture said, That ye may learn them and observe to do them,  whosoever is [engaged] in observance  is [also regarded as engaged] in study, but whosoever is not [engaged] in observance is not [regarded as engaged] in study. And if you wish I may say: [The reading is] in fact, as was said before: 'Whosoever says that he has only [an interest in the study of the] Torah has only [reward for the study of the] Torah', yet [the statement] was necessary [in the case] where he teaches others and these go and do observe [the laws of the Torah]. Since it might have been assumed that he also receives reward,  hence we were taught [that he does not]. And if you wish I may say [that the statement] 'who rivets himself to the word of the halachah' [applies] to a judge who, when a lawsuit is brought before him, and he knows of an halachah [relating to a similar case], compares one case with the other  and, though he has a teacher, he does not go to him to inquire.  [Such a judge brings evil upon himself] for R. Samuel b. Nahmani stated in the name of R. Jonathan: A judge should always imagine himself as if [he had] a sword lying between his thighs, and Gehenna was open beneath him; as it is said in Scripture, Behold, it is the couch  of Solomon; threescore mighty men  are about it, of the mighty men of Israel etc. because of the dread in the night:  'because of the dread of' Gehenna  which is like 'the night'. R. GAMALIEL SAID: IF SHE EXERCISED HER RIGHT OF MI'UN etc. R. Eleazar inquired of Rab: What is R. Gamaliel's reason?  Is it because he holds the opinion that the betrothal of a minor remains in a suspended condition  and as she grows up it grows with her  even though no cohabitation has taken place;  or is the reason because he is of the opinion that when a man betroths the sister of his sister-in-law the latter procures her exemption thereby, but thereby only,  [and consequently] only if cohabitation has taken place is the elder sister exempt,  but if no cohabitation has taken place she is not? — The other replied, This is R. Gamaliel's reason: Because he is of the opinion that when a man betroths the sister of his sister-in-law the latter procures her exemption thereby but thereby only  [and consequently] only if cohabitation has taken place is the elder sister exempt,  but if no cohabitation has taken place she is not. Said R. Shesheth: It seems  that Rab made this statement while he was sleepy and about to doze off;  for it was taught: If a man betrothed a minor, her betrothal remains in a suspended condition. Now, what [is meant by] 'a suspended condition'? Obviously  that as she grows up it grows up with her  even though there was no cohabitation.  Said Rabin the son of R. Nahman to him: The matter of the betrothal of a minor  remains in a suspended condition. If cohabitation had taken place  it is valid, but if no cohabitation had taken place  it is not; for [in the absence of such cohabitation] she thinks 'He has an advantage over me  and I have an advantage over him'. Is Rab, however, of the opinion that only if cohabitation had taken place is the betrothal valid,  but if there was no cohabitation it is not? Surely it was stated: Where a minor did not exercise her right of mi'un and, when she became of age, actually  married [another man], Rab ruled: She requires no letter of divorce from her second husband, and Samuel ruled: She requires a letter of divorce from her second husband.