Ketubot — Daf 73a

לא תימא טעמיה דרב כיון שכנסה סתם אחולי אחליה לתנאיה אלא טעמא דרב לפי שאין אדם עושה בעילתו בעילת זנות

הא פליגי בה חדא זימנא דאתמר קטנה שלא מיאנה והגדילה עמדה ונישאת רב אמר אין צריכה גט משני

ושמואל אמר צריכה גט משני

צריכא דאי אתמר בההיא בההיא קאמר רב משום דליכא תנאה אבל בהא דאיכא תנאה אימא מודי ליה לשמואל

ואי אתמר בהא בהא קאמר שמואל אבל בהך אימא מודי ליה לרב צריכא

תנן כנסה סתם ונמצאו עליה נדרים תצא שלא בכתובה כתובה הוא דלא בעיא הא גיטא בעיא מאי לאו קידשה על תנאי וכנסה סתם תיובתא דשמואל

It must not be suggested that Rab's reason  is that, because the man has married her without attaching any conditions, he has entirely dispensed with his former condition.  Rab's reason rather is that no man treats his intercourse as a mere act of prostitution. Surely they  once disputed on such a principle.  For it was stated: Where [an orphan] minor  who did not  exercise her right of mi'un  and who, when she came of age, left  [her husband]  and 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!  — [Both disputes were] necessary. For if the latter  only had been stated, it might have been assumed that Rab adhered to his opinion  in that case only because no condition was attached [to the betrothal],  but that in the former case,  where a condition was attached [to the betrothal],  he agrees with Samuel.  And if the former case  only had been stated, it might have been assumed that in that case only  did Samuel maintain his view  but that in the latter  he agrees with Rab.  [Hence both were] required. We have learned: IF HE MARRIED HER WITHOUT MAKING ANY CONDITION AND SHE WAS FOUND TO BE UNDER A VOW, SHE MAY BE DIVORCED WITHOUT RECEIVING HER KETHUBAH [which  implies that] it is only her kethubah that she cannot claim but that she nevertheless requires a letter of divorce. Now does not this  refer to one who has betrothed a woman on condition [that she was under no vow]  and married her without making any condition?  This then  represents an objection against Samuel!