Gemara

(Rava): (An orphaned girl cannot marry mid'Oraisa until she matures. Chachamim enacted marriage mid'Rabanan for her, and allow her to do Mi'un, i.e. retroactively annul the marriage, until she matures.) A girl may do Mi'un anytime until 12 full years, but not after 12.

We are concerned lest she brought hairs after 12 years, and they fell out (and the marriage became mid'Oraisa).

(Rav Dimi of Neharde'a): The Halachah is, (regarding Mi'un) we are concerned lest they fell out.

This is only if she had Bi'ah with her husband after 12 years of age, for then it is a Safek mid'Oraisa. If not, she may do Mi'un.

Yevamos 33b (Mishnah): If two brothers were Mekadesh two sisters, and they switched wives, they are liable for Eshes Ish, Eshes Ach, Achos Ishto and (if they were Nidos) Nidah.

34a: The Isurim of Eshes Ish, Eshes Ach and Achos Ishto can come all at once if the brothers' Shali'ach gave Kidushin money to the sisters' Shali'ach;

(Rav Amram): The Isurim of Nidah can simultaneously with the other Isurim if the girls were Nidah when they became (adults, at) 12, and when the boys turned 13.

109b (Beraisa): If one is Mekadesh a minor, the Kidushin is tentative.

Suggestion: When she grows up, it becomes mid'Oraisa even without Bi'ah.

Rejection (Ravin brei d'Rav Nachman): No, it becomes mid'Oraisa only if they have Bi'ah after she matures.

(Rav): If a minor (married mid'Rabanan) did not do Mi'un, and she married David after she matured, she does not need a Get from David;

(Shmuel): She needs a Get from David.

Suggestion: The case is, she did not have Bi'ah with her first husband after maturing.

Rejection: No, they had Bi'ah.

Kidushin 62a (Mishnah): If a man was Mekadesh a woman to take effect after one of the following, it is invalid even after it occurs:

After he or she converts or is freed;

After the death of her sister (who is his wife), or her husband;

After she does Chalitzah.

Question (Rav Asi): If one said 'detached Peros of this patch should be Terumah on the attached Peros of this patch when they are picked', does this work?

Answer (R. Yochanan): If something cannot take effect until an action is done, if it is b'Yado (under his control), it is if it was done.

62b - Question (R. Aba bar Mamal): If so, if one is Mekadesh his Shifchah to take effect after he frees her, it should work (since it is b'Yado)!

Answer: After freedom, the Shifchah has Da'as (intent for Kidushin), but not beforehand.

Suggestion: R. Yochanan would argue about R. Oshaya's law!

(R. Oshaya): If Shimon gave to his wife a Perutah and said 'you are Mekudeshes to me after I will divorce you' she is not Mekudeshes.

Rejection: No. Granted, Shimon can divorce his wife, but he cannot be Mekadesh her again without her consent.

Bechoros 49a (Rav): If Pidyon ha'Ben was done within 30 days, it is valid;

(Shmuel): It is invalid.

They argue when he gave now to take effect after 30 days, and the Kohen does not have the money then;

Rav says that it is valid, just like Kidushin (given to take effect after 30 days. It is valid, even if the money was already consumed);

Shmuel says that Kidushin is different, for he could be Mekadesh her right now, but Pidyon cannot be done within 30 days.

Kesuvos 59a (Mishnah): If a wife vowed 'what I earn is forbidden to your mouth', her husband need not annul it;

R. Yochanan ben Nuri says, he should annul it, lest he divorce her and be unable to remarry her.

(Shmuel): The Halachah follows R. Yochanan ben Nuri.

Question: If something does not become Hekdesh now, can it become Hekdesh later?!

Answer (Rav Papa): Yes! If one said 'the field that I mortgaged to you for 10 years (the lender eats the Peros and deducts from the loan) will be Hekdesh when I redeem it', it becomes Hekdesh.

Objection (Rav Ashi): There, he can redeem the field after 10 years. A wife can never divorce herself!

Rishonim

Rambam (Hilchos Ishus 4:7): If a minor was Mekadesh, it is invalid.

Mishneh l'Melech: A Mishnah clearly teaches this. If he said 'you are Mekudeshes to me after I mature', or if an adult man said to a minor girl 'you are Mekudeshes to me after you mature', what is the law? Since they were minors at the time of Kidushin, it is invalid. Or, since he stipulated that Kidushin will take effect when they are adults, it takes effect? We cannot learn from the Mishnah (62a), which discusses Davar she'Lo Ba l'Olam. I.e. he cannot be Mekadesh her until an action, i.e. conversion, freedom, or death. Here, the time comes by itself. Perhaps this is Ba l'Olam. We do not permit a vow until it takes effect. Some say that this is only if it is Mechushar Ma'aseh, but not if it is only Mechusar Zeman, for time comes by itself. Gitin 85a) asked whether a Get that does not permit her to become Mekudeshes to a minor is valid. Now he cannot be Mekadesh, but later he can.

Nimukei Yosef (Yevamos 37b DH Gemara): The Gemara had two ways to explain one who was Mekadesh a minor. Perhaps it is like Kidushin 'after 30 days'. If she does not retract within 30 days, she is Mekudeshes mid'Oraisa after 30 days, even if the money was consumed. Or, perhaps the Kidushin depends on Bi'ah after maturity.

Magihah in Mishneh l'Melech: The Nimukei Yosef and Rashba connote that this is only for a man who was Mekadesh a minor girl, but if a boy was Mekadesh for after he will mature, this has no effect.

Mishneh l'Melech: Later, Rashi and Tosfos (Yevamos 34a) argue about this. All the Isurim can take effect at once if the girls were Nidah when they turned 12 and the boys turned 13. Rashi explains that the boys were Mekadesh on the day that completed 12 and 13 years. The Kidushin takes effect the moment they mature. Tosfos disagreed, for a minor cannot be Mekadesh or make a Shali'ach. His actions have no effect, i.e. even if he stipulates that it take effect later. The Maharit asked why Rashi specified that they were Mekadesh on the day that they finished 12 and 13 years.

Mishneh l'Melech: Rashi holds like R. Tam and the Rosh, that two hairs on the last day of 12 years make her an adult. Even though she is a minor until night, the Kidushin works. Since they already have hairs they are not Mechushar Ma'aseh, only Mechusar Zeman. Before they brought hairs, perhaps they are like Mechushar Ma'aseh. Hairs come by themselves, but they are unlike time. Time is guaranteed to come, unlike hairs; it is not within their control. Before the day before the years finish, hairs are not Simanim of adulthood.

Note: Adulthood comes even without hairs (after 35 years), but then the person is a Seris or Ailonis (does not have normal sexual development, and is sterile). The Kidushin would be invalid unless they stipulated for this, which is very rare. If Rashi applied 'Mechusar Zeman does not apply to the same day' even to matters that occur immediately at nightfall (e.g. adulthood), we could say that this is why he discussed the last day.

Aruch ha'Shulchan (EH 43:4): If a minor was Mekadesh to take effect 'after I mature', it does not work. It is Davar she'Lo Ba l'Olam. The Mishneh l'Melech was unsure if something that comes automatically after time is Ba l'Olam. The Mordechai in the first Perek of Bava Metzi'a (perhaps he refers to Remez 247 - PF) explicitly says that it is. Many are unsure about this, so it is Safek Kidushin. If one was Mekadesh on the day that completes 13 years, all the more so it is a Safek, since Mechusar Zeman does not apply on the same day for Kodshim. However, some argue about Kodshim (Tosfos Menachos 5a DH v'Iy), and this is only for the same day, but not for the next day. Perhaps it is Vadai Kidushin if he already brought hairs. See Tosfos Nidah 49a DH v'Iba'is. Yevamos 34a connotes that such Kidushin works (according to Rashi), but it is like the opinion that one can transfer ownership of Davar she'Lo Ba l'Olam. This is not the Halachah.

Mishneh l'Melech: Pidyon ha'Ben before 30 days is invalid, but one can stipulate that it take effect after 30 days, since the time comes by itself. Likewise, if one said 'the field that I mortgaged to you for 10 years will be Hekdesh when I redeem it', it takes effect, because he can redeem it after 10 years. There, even though it is Mechushar Ma'aseh (redemption), it works because it is b'Yado. Even though now it is not b'Yado, since the only impediment is time, it is not considered Mechushar Ma'aseh. All the more so Kidushin takes effect, for no action is lacking. Likewise, if a slave received a document of freedom to take effect after a fixed time, she can receive Kidushin to take effect after the time, for only time is lacking, and it comes by itself. Shmuel holds that the Kidushin takes effect only if the money is intact; Rav disagrees.

Poskim

Shulchan Aruch (EH 43:1): If a minor was Mekadesh or married a woman, this has no effect.

Avnei Milu'im (1): The Mishneh l'Melech said that Rashi and Tosfos argue Kidushin 'after I mature'. He supported Rashi from stipulations for Pidyon ha'Ben after 30 days, or to be Makdish a field after he redeems it. What is b'Yado after time takes effect, and all the more so Kidushin, which is not Mechushar Ma'aseh at all. The Magihah brought that the Nimukei Yosef holds like Rashi, even if the money was consumed, since (if not for the Kidushin) she still owes the money, i.e. if a man was Mekadesh a minor, for Chachamim enacted such a marriage. There was no enactment for a (minor) boy, so this reason does not apply.

Avnei Milu'im: The Nimukei Yosef said that the Kidushin depends on Chachamim's enactment based on the Rashba, who said that the Kidushin matures with her. Mid'Oraisa there is no Shibud (obligation) on her, for "Ki Yiten Ish El Re'ehu" excludes a minor. However, Chachamim enacted marriage for a minor girl, so there is Shibud of Kesef Kidushin. If a boy was Mekadesh an adult, mid'Oraisa there is Shibud. Surely one must return to a minor! The Rambam and Shulchan Aruch (CM 96:3) hold that Shevu'as ha'Shomrim applies to what a minor deposited! The Rashba holds that there is no Shemirah for a minor, i.e. one is exempt for negligence, but if the deposit is intact, one must return it. Also, if one consumed the deposit and benefited from it, surely he must pay the minor. If so, the woman has a Shibud to the minor for the Kidushin money, and she is Mekudeshes mid'Oraisa, even though there was no enactment of Kidushin for a boy.

Avnei Milu'im: The Mishneh l'Melech discussed a boy who was Mekadesh a minor. There, there is no Shibud, and there is no Nisu'in for a boy, even mid'Rabanan. Really, a boy's Kidushin s void, even if he stipulated 'after maturity.' If one is Mekadesh his Shifchah 'after I will free you', it does not work, for she has Da'as only after freedom. Rashi says that this is the ultimate Mechushar Ma'aseh. R. Yochanan could agree with R. Oshaya (that 'you are Mekudeshes to me after I will divorce you' does not work). Rashi explained that it is because he cannot be Mekadesh her again without her consent. Why is this unlike Kidushin after 30 days?! Rather, since now both agree, it is not Davar she'Lo Ba l'Olam, since he could be Mekadesh her now. The same applies to Kidushin after divorce! The Ritva says that he could not be Mekadesh her now until after divorce, so a total Ma'aseh is lacking. This is unlike attached Peros, for one can detach them, and this completes the Ma'aseh. I do not understand his distinction between a big and small Ma'aseh. Also, whatever is b'Yado is not Mechushar Ma'aseh at all! Rather, Kidushin after 30 days works, but not Kidushin after divorce, since it could not take effect now. It is not Davar she'Lo Ba l'Olam, because it is b'Yado, but consent now (for Kidushin) does not help, for perhaps she will not consent after divorce, whereas Terumah needs only his Da'as. If a minor is Mekadesh 'after I mature', it is not Davar she'Lo Ba l'Olam, since it is only Mechusar Zeman, but it is no better than something b'Yado. It is not Kidushin, for perhaps she will not consent later.