Gemara

(Beraisa - Rebbi): If Reuven sold (a field) to Shimon for 100, and Shimon sold to Levi for 200, Reuven redeems according to the first sale (price).

If Reuven sold to Shimon for 200, and Shimon to Levi for 100, Reuven redeems according to the second sale.

Bava Metzia 79b (Beraisa): If Reuven rented Shimon's ship and unloaded his cargo in mid-journey, he pays the rental for the amount traveled. Shimon has only complaints.

Question: If Shimon can find someone else to rent the ship for the rest of the way, why does he have complaints?

If he cannot find someone else to rent it the rest of the way, Reuven should pay the full fare!

Bava Basra 30a: Reuven asked Shimon: What are you doing on this land?

Shimon: I bought it from Ploni. He said that he bought it from you.

Reuven: You admit that it was mine, and you did not buy it from me. Go away! You have no case against me.

(Rava): The law is like Reuven said.

Rishonim

Rambam (Hilchos Sechirus 5:5): If Reuven rented a house to Levi for a set time, and Levi wants to rent it to Shimon, he may rent it until the end of the time, unless Shimon's household is bigger. A renter may not rent the item to others only regarding Metaltelim, for the owner can say 'I do not want my deposit to be in others' hands.' Regarding a house or boat, in which the owner is with it, he cannot say so. Similarly, if Reuven said 'why toil to rent my house to others? If you do not want to stay, leave, and I exempt you from the rent', he may not rent it to others. If one benefit another without loss, he must do so. Instead of renting it to others, leave him with his house. One opinion ruled that he cannot rent it to another at all; he must pay full rent until the end of the time. I disagree.

Ra'avad: In our generation some say (they he cannot rent it to another at all), for some people destroy the house they dwell in.

Magid Mishneh: The Rambam learns from the case of a boat. Only there the owner has complaints, for he must live with the renter and it is hard to bear different mindsets. Regarding a house, there is no reason for complaints. Presumably, the opinion that the Ra'avad cites would say that a boat is different, for the owner is with it. He can guard that the renter not ruin it. In any case it is a weak claim, for if the second renter damages, he must pay. Damage to (what is attached to) land is rare, so he cannot say 'I do not want my deposit in others' hands.'

Taz (CM 316:1): Even if the owner of the land is not there, he can go at any time to investigate what is happening in his house.

Rambam (Hilchos Mechirah 23:8): The difference between buying a field for its Peros and renting is that the former may plant (trees) or seed whatever he wants or leave it fallow. A renter may not, and he may not rent it to another. One who bought may be Makneh (transfer ownership) to others whatever he bought.

Mordechai (Bava Basra 529): If Reuven rented a house to Levi for 10 years and paid all the rent, and after two years Levi bought a house and moved there, and rented Reuven's house to Shimon, and Reuven does not consent for Shimon to live there, we learn from Bava Basra. Shimon said 'I bought from Ploni, who said that he bought it from you.' Reuven can say 'go! You have no case against me.' The same applies here. If Levi wants back the rent he paid, Reuven can say 'the house is in front of you. You may live in it, but I do not let you bring others in.' even if Levi did not yet pay all the rent, he must pay. From when he was Machazik (occupied the house), he is liable to pay the entire rental. Rental is acquired through Chazakah, or even through giving over the key. This is if he cannot find someone else to rent it. If he can find someone else for the same rent, Levi pays only for the two years. This is like David who rented Moshe's ship and unloaded his cargo in mid-journey. If Moshe can find someone else to rent the ship for the rest of the way, he has no complaints (or claim) against the renter. If not, David must pay the full fare! The same applies to a house. However, he must inform him 30 days before winter. A Sifri says that just like the landlord must tell the tenant (in advance before evicting him), also a tenant must tell the landlord. The landlord can say 'had you told me in advance, I could have toiled to find proper tenants.' After Reuven received and acquired the rental, Levi cannot say 'return it to me, and I will rent it to another.' When Levi leaves, the house is in Reuven's Chazakah. We hold like Rav Nachman, that land is the owner's Chazakah, and not in the tenant's Chazakah. Reuven can rent it to whom he wants. Levi cannot say 'since I paid rent, it should be vacant.' Reuven did not rent it so that it will be desolate. An inhabited house endures (Bava Kama 21a).

Beis Yosef (Sof Siman 312 DH Kasav Mordechai): Most of this is incorrect, to one who thinks about it, except for his final words 'Levi cannot say 'since I paid rent, it should be vacant... an inhabited house endures.

Darchei Moshe (1): The Mordechai permit renting it to a bigger household. Mahariyo (10) says similarly. However, the Mordechai brought from Maharam that Levi cannot sublease it, and if someone lived there, he must pay rent to the owner. If Levi does not want to live there, he must pay the full rent. He may not bring others in. However, if Reuven can find someone else to rent it, Levi pays only for what he lived there. However, if Levi already paid all the rent, even if Reuven can rent it to someone else, he does not return Levi's money. Reuven may rent it to whom he wants. Levi cannot say 'since I paid rent, it should be vacant.' The Beis Yosef rejected the Mordechai, because he holds that one may rent it to others, like the Rambam and Maharam. The Rambam and Maharam argue about whether one may rent it to more people. We hold like the Rambam, for we follow the Chazakah regarding every Safek about land. Therefore, he cannot rent it to anyone harsher. The Rashba connotes like this.

Mordechai (Bava Metzia 357, citing Maharam): We learn from the boat that if Reuven rented a house to Shimon, Shimon can put Levi in place of himself. Reuven has only complaints due to different mindsets. A renter may not rent the item to others only regarding Metaltelim, for the owner can say 'I do not want my deposit to be in others' hands', or 'I do not trust his oath' (if it will be lost through Ones). Regarding land, a borrower may lend and a renter may rent, if he already made a Kinyan on the land. Just like money, a document or Chazakah acquire (a purchase) of land, they acquire rental of land. Also, Shimon may fill the house with tenants, e.g. teachers, scribes, hired hands and residents, like anyone who rents a house. There is no limit how many people one may put in a house. A Mishnah (Bava Basra 59b) permits building onto one's house an inner room or second story. He may not increase traffic in the Chatzer; rather, he merely split a room into two (60a). This is permitted, for one may fill his house with residents. If Levi rented from Reuven, and it was found to be Shimon's, he pays Shimon (Bava Kama 21a). We say that this discusses a Chatzer destined to be rented. I.e. but if not, he is exempt. All the more so here, it is not destined for Reuven to rent it out, since he already rented it to Shimon. Levi need not pay Reuven; he pays Shimon, for it is acquired to him. Another proof is from Erchin. If Reuven sold to Shimon for 100, and Shimon sold to Levi for 200, or if Reuven sold to Shimon for 200, and Shimon to Levi for 100, Reuven redeems for 100. Selling a field when Yovel applies to is like mere rental, since it returns in Yovel. Even so, a buyer may sell to another without the owner's Reshus.

Gra (CM 316:1): Surely, the buyer may sell without the owner's permission. If not, what is the Chidush? Do we discuss a fool (who would allow the buyer to resell for a higher price, if this will increase the amount he must pay to redeem it)? Do not say that he sold it b'Isur. If so, surely this does not increase the redemption!

Poskim

Shulchan Aruch (CM 316:1): If Reuven rented a house to Levi for a set time, and Levi wants to rent it to Shimon, he may rent it until the end of the time, as long as Levi's household is no bigger than Shimon's. If Reuven said to him 'why toil to rent my house to others? If you do not want to stay, leave, and I exempt you from the rent', we heed him.

Gra (1): Metaltelim are different, for they can be stolen and hidden. We learn from Ma'aser Sheni 5:9. R. Gamliel gave (what he will separate to be) Ma'aser Rishon to R. Yehoshua, and rented its place to him. R. Yehoshua gave (what he will separate to be) Terumas Ma'aser to R. Elazar ben Azaryah, and rented its place to him (even though he rented the place from R. Gamliel).

Note: What is the proof? This was in front of R. Gamliel. His silence showed consent. How does this prove that a renter can rent against the owner's will?

Gra: Also, one may write a Pruzbul on a tenant's land (Gitin 37a). If a tenant cannot sublease, his creditor could not collect it from him, so one may not write a Pruzbul on it! The Yerushalmi says that we do not heed a widow who wants to rent out the quarters she is entitled to. This connotes that normally, one may rent it out! (Rashba 1145, 1153).

SMA (3): The Mordechai says that if Reuven already received the money, he need not return it to Levi. Even if Levi says 'leave the house vacant', Reuven need not listen. However, if Levi did not yet pay, and Reuven rents it to others, we deduct the rent from Levi's debt. If Levi says 'I will pay everything. Do not rent it to others', according to letter of the law we should not heed him. However, since he agreed to pay only if no others will live there, and others lived there, we cannot force him to pay.

Ketzos ha'Choshen: The Rema omitted the Mordechai's opinion, who distinguishes between whether or not Levi already paid all the rent. Why does the SMA bring the Mordechai, after the Beis Yosef and Darchei Moshe rejected it? Toras Emes (208) says that perhaps the Rambam discusses only when Reuven did not yet receive all the rent, but if he did, the Rambam agrees with the Mordechai. I say that we follow the Beis Yosef and Darchei Moshe.

Ketzos ha'Choshen (2): The Mordechai connotes that if Levi already paid, even if Reuven rented it to others, he keeps all the rental. How can he do business with another's property?! The house itself is acquired to Levi. Even if the Mordechai holds that Levi cannot rent it to others, and even so he must pay all the rent, if Reuven rented it to others, why does he get double rental?! He should return the latter rental to Levi! The Mordechai is unlike the SMA says. He said only that if Levi already paid, he cannot rent it to others or say that it must be vacant, because an inhabited house endures. For this it is in Reuven's Chazakah. Reuven may leave it vacant, or house someone in it for free, for desolation ruins a house. However, if he rents it to another, the Mordechai admits that Levi gets the rental, since he acquired it for rental.

Ketzos ha'Choshen: Maharam (Bava Metzia 345) argues with the Mordechai. Leah rented a house and died. Her heirs wanted to pay only for the time she lived there. Maharam said that if she did not yet pay, her heirs are exempt, since it was Ones. If she already paid all the rental, her heirs can put in it someone similar, but not someone harsher than her. The Mordechai distinguishes between when all the rent was already paid, or not. He holds that Yovel is different, because the Rambam says that a renter may not rent to another, but one who bought may be Makneh to others whatever he bought. Buying a field when Yovel applies is even better, for he may build and destroy. Therefore, he may sell it. Since Maharam holds that even if he received the minority, he may rent it to others, we hold like him.