Gemara

(Rav Dimi citing R. Yochanan): If Reuven told Shimon 'do Meshichah on this cow (take it to your premises), but it is not yours until 30 days from now', 30 days later he acquires it, even if it is in a swamp.

Contradiction (Ravin citing R. Yochanan): The cow is not acquired 30 days later.

Answer: Rav Dimi discusses when he said 'acquire from now.' In Ravin's case, he did not say this.

86b - Question (Rami bar Chama): If her husband gave her Get and said 'you are not divorced until 30 days from now' and she left the Get in Tzidei (the side of a) Reshus ha'Rabim (and it was still there at the end of 30 days), what is the law?

Answer: We learn from Rav Nachman that she is divorced!

(Rav Nachman): If Reuven told Shimon 'be Moshech this cow, but it is not yours until 30 days', he acquires it then, even if it is in a swamp.

Kidushin 58b (Mishnah): If Reuven told Leah 'you are Mekudeshes to me after 30 days', and Moshe was Mekadesh her during the 30 days, she is Mekudeshes to Moshe. If Moshe is a Kohen and Leah is a Bas Yisrael, she may eat Terumah.

If Reuven told Leah 'you are Mekudeshes to me from now and after 30 days', and Moshe was Mekadesh her during the 30 days, she is Mekudeshes and not Mekudeshes. If he is a Kohen and she is a Bas Yisrael, or he is a Yisrael and she is a Bas Kohen, she may not eat Terumah.

59a - Question: What is the law if no one was Mekadesh her in the interim?

Answer (Rav and Shmuel): She is Mekudeshes, even if the Kidushin money has been consumed. This is because the Kidushin money is not a loan, nor a deposit;

It is not a deposit. A deposit belongs to the giver, whereas this money belonged to her.

It is not like (pardoning a) loan (that she owes to him). A loan was given to be spent (from the beginning), and when he is Mekadesh her later, he does not give her anything (new). Here, he gave the money for Kidushin!

Nedarim 48b: Yakov forbade his property to his son Levi, then was Makneh to Levi to give to Levi's son, if Levi will have a son who is a Chacham. Rav Nachman ruled that this works; Rav Ashi questioned it.

Rishonim

Rosh (9:15): Rav Nachman taught that if Reuven told Shimon 'do Meshichah on this cow, but it is not yours until 30 days from now', 30 days later he acquires it, even if it is in a swamp!

Hagahos Ashri (8:13:3): R. Yochanan taught that Meshichah of a cow to acquire after 30 days works even if it is in a swamp, but not if it is in Reshus ha'Rabim. The Ri says that this is when he said 'from now'. If not, he does not acquire. Likewise, if one acquires a field through Chazakah (to take effect after 30 days), he must say 'from now'. The same applies to a document to acquire a field or a Shtar Kidushin that became torn or lost during the 30 days. (It is valid only if he said 'from now'.) However, if he bought a field or was Mekadesh with money, it is valid even if the money was consumed, even without 'from now'. If she would not be Mekudeshes, she would need to pay. Therefore, it is as if the money is intact. Regarding Meshichah, if he did not say 'from now', the Meshichah ceased.

Lechem Mishneh (Gerushin 9:2): Rashi holds that the Safek whether 'from now and after 30 days' is a Tnai or retraction applies only to Kidushin. Regarding objects, he gives the item itself now, and the Peros after 30 days.

Mordechai (Kidushin 526): When one says 'be Moshech this cow to acquire from now and after 30 days', why don't we have a Safek if this is a Tnai or a retraction? It seems that the Safek is only regarding Kinyan Kesef, which works without 'from now'. R. Baruch says that the Safek is only when he said 'but do not acquire until after 30 days.'

Ran (Nedarim 48b DH Amrei): Yakov's gift to Levi to be Makneh to Levi's son is unlike a gift on condition to return it. There, the recipient may use it while he has it. Here, Levi received no rights in the property. The Kinyan to Levi is Batel before Levi's son receives, whether Levi acquired through Chalipin or Chazakah. Rav Nachman agrees that Meshichah to acquire after 30 days does not acquire if the cow is in the swamp after 30 days. Here, since Yakov did not specify that Levi not acquire until he has a son who is a Chacham, it is as if he said 'from now'. Rav Ashi disagrees. Yakov wanted to give only to the grandson; he did not want Levi to acquire beforehand. The Rashba applies this to Chalipin, Meshichah and Chazakah, in which the Kinyan ceases. Acquisition through a document works, for the document endures forever. Kidushin through a document to take effect after 30 days is valid if the document is intact. The same applies to divorce. I say that even a document would not help here. Yakov was about to die; a document cannot acquire after death. This is why Rav Ashi argued Stam (without specifying how he acquired).

Poskim

Rema (CM 191:4): If one sold land with a document or money and said 'acquire after 30 days' and the document was torn or the money was lost in the interim, the buyer acquires only if the seller said 'acquire from now and after 30 days.' The same applies to Chazakah.

Beis Yosef (197 DH v'Chosvu ha'Tosfos): Tosfos (Yevamos 93a DH Kenuyah) says that a Chazakah or Chalipin to take effect after 30 days does not work, because the Chazakah ceased or the garment was returned, just like Meshichah does not help for after 30 days because it ceased. The same applies if the document was torn in the interim. Tosfos implies that if one bought land with money where they do not write documents, or if he stipulated to acquire through money, it works even if he did not say 'from now', and even if the money was consumed. This is because if the sale will be invalid, the money must be returned.

SMA (9): The Darchei Moshe (3) says that the Beis Yosef says that also if the money was lost in the interim, the buyer acquires only if the seller said 'from now.' The Beis Yosef did not say so here; elsewhere, he cites Tosfos to say that we are not concerned if the money was lost in the interim! Perhaps here the Rema refers to a case in which the money was lost and the seller cannot get it back. He inferred that the Beis Yosef validates the Kinyan only when the buyer would need to return the money if the Kinyan were cancelled. Alternatively, the Rema's words 'Oh b'Ma'os' (or with money) are a mistake. It should say 'uv'Ma'os'. He refers to a place where money and a document are needed to acquire. He mentions losing the money only to teach that when he said 'from now', the sale is valid even if the document was torn and the money was lost. Really, it never matters whether or not the money was lost.

Rebuttal (Taz): The SMA could have asked from the Gemara itself (Kidushin 59a), which says that Kidushin works even if the money was lost in the interim. The SMA's first answer is wrong. Rashi says that Kidushin money is not like a loan; they are in her Reshus when she consumes them. This is why the Kidushin works. According to the SMA, it is a loan! Tosfos (Yevamos 93a DH Kenuyah) agrees with Rashi. We rely on the SMA's second answer. He revealed his intent that the money should acquire only when the document does. Therefore, if the money was lost in the interim, it does not acquire.

Question (against SMA - Ketzos ha'Choshen 3): It does not matter whether or not she can repay! Perhaps indeed, the SMA means that the Rema discusses when the money was lost b'Ones and she need not return it. However, it seems that even in such a case, she must return the money if she retracts. If money was given for Kidushin or a sale, if she or the buyer retracts, (s)he is a thief, and is liable even for Ones. The Rosh (Sukah 3:30) says similarly about a gift on condition to return it.

Yad ha'Melech (Hilchos Ishus 7:10 DH ha'Maharit and DH v'Kivan and Gerushin 8:1): Tosfos in Yevamos, the Rashba and Ran says that even if she consumed the money, she is Mekudeshes, for if not she would need to pay. The Maharit (Kidushin 59a) says that if the money was lost or stolen, even through negligence, she is exempt, so she is not Mekudeshes. Perhaps the Rema holds like the Maharit. This is unlike Tosfos (Kidushin 60b DH Ika), who says that in either case she is Mekudeshes. This is more reasonable to me. Since she gets Hana'ah (benefit) from Kesef, she can be Makneh herself to take effect at any future time. Other Kinyanim are Gezeras ha'Kasuv, so they must be like the Torah specified; the Kinyan must endure.

Question (Taz): R. Yochanan holds that 'from now and after 30 days' is a long Meshichah, therefore it helps if it is in a swamp at the end of 30 days. The Rosh and Tur rule like Rav (regarding such a Kidushin), who is unsure whether or not it is a Tanai. If so, it does not help to be in a swamp at the end! Why do the Beis Yosef and Rema say that 'from now and after 30 days' helps even if the document was torn in the interim? Even R. Yochanan does not say so, only Shmuel. The Poskim argue about whether the Halachah follows Rav or R. Yochanan, but no one rules like Shmuel! We can answer for the Rosh that when he says 'do not acquire until...', all agree that this is not Chazakah (it seems that this should say Chazarah (a retraction).)

Gra (9): In EH (40:4), the Shulchan Aruch is concerned for R. Yochanan's opinion that 'from now' does not help because it means that he leaves his acquisition incomplete. Regarding Meshichah to acquire 'from now and after 30 days', the Rambam and Shulchan Aruch (CM 197:7) require the cow to be in a swamp after 30 days, but not in a Reshus ha'Rabim. Here, the Shulchan Aruch rules like the Magid Mishneh, Ramban and Rashba, who rule unlike the Sugya on 86b, and unlike R. Yochanan (regarding Kidushin).

Lechem Mishneh (Hilchos Mechirah 2:9): It seems that the Rambam rules like Shmuel, who says that 'from now' is surely a Tanai. Regarding Kidushin, he is stringent for Rav's opinion that perhaps it is a retraction. However, we follow Rav against Shmuel in Isur, and they argue primarily about Isur. Also, we follow R. Yochanan against both of them! Perhaps he holds that Rav and R. Yochanan are stringent about Kidushin, but agree regarding money.