Gemara

(Rav Papa): In a place where the borrower can redeem Mashkanta (the lender eats the Peros of the borrowers' land for a fixed time), (if the lender dies,) his creditor does not collect from it.

Bava Kama 118a (Mishnah): If Reuven received a deposit or borrowed from Shimon in a Yishuv (settled area), he may not return to him in the Midbar (wilderness).

Contradiction (Beraisa): A loan may be paid anywhere. An Aveidah or deposit may be returned only to its place.

Answer (Abaye): The Beraisa means that one may demand payment of a loan anywhere. One may demand an Aveidah or deposit only in its place.

Gitin 74b (Mishnah): At first, one who bought a house in a walled city would hide on the last day the seller could redeem it. Hillel enacted that the seller may deposit the redemption money in a chamber and forcibly enter the house.

Kesuvos 81b - Question: If we consider the Kesuvah to be collected in his lifetime, a Yavam could designate an amount sufficient to pay the Kesuvah and sell the rest (of his brother's property)!

Bava Basra 145a (Beraisa): Shushbinus (gifts that one brings to his friend's nuptial feast) is repaid at the proper time (when the giver gets married).

Makos 3a (Mishnah): If witnesses testified that Reuven must pay to Shimon 1000 Zuz in 30 days, and Reuven says that he has 10 years to pay, and they were Huzam, we estimate the difference of what one would pay for rights to have 1000 Zuz for 30 days or for 10 years. (They tried to make Reuven lose this.)

Rishonim

Ramban (Teshuvah 34): If a borrowed wants to pay before the time, the lender cannot refuse. He did not accept the money to be in his Achrayus. We say that where one can redeem Mashkanta early, the lender's creditor does not collect from it (after the lender died).

Ran (Kesuvos 40a DH v'Garsinan): Some learn from our Gemara that a borrower cannot pay a loan earlier to end the lien against him. This is wrong. The time (for paying the Kesuvah) is also to help her. A husband cannot pay in advance, lest it be light in his eyes to divorce her. The date in a regular loan is purely for the borrower's benefit. The Ramban learns this from a place where the borrower can redeem Mashkanta before the time fixed for the loan, because the time is for his benefit. Even though in places where one cannot redeem before the time, they hold that the time is for the benefit of both of them, and neither can claim or pay before the time, this is because the lender is like a buyer. Regarding a loan, all agree (that he can pay early). Also, where there is no custom, one may redeem Mashkanta early.

Rashbam (Bava Basra 145b DH Nigbis): Shushbinus was given with intent that the receiver return it when the giver gets married. Payment is according to the time that the lender fixed.

Gra (CM 74:9): The Ra'avad says that it cannot be returned before the time. It is like a loan, i.e. in such a case.

Poskim

Shulchan Aruch (CM 74:2): If the lender (David) fixed a time for the borrower (Levi), and Levi wants to pay earlier lest he have responsibility for the money until then, and David does not want to accept it:

If the time already came, even if Levi rushes to pay to save himself from coming Onesim such as currency changes, taxes and conscription (for the king's service), he may do so. The problem is not here yet, even though it will come tomorrow or even the same day after payment. He need not be concerned for David's loss.

Shach (9): Maharshach says that if David is not here, Levi can give the money to Beis Din or a party that Beis Din trusts, even though there was no enactment like this, and the lender does not know about the Ones. This was done in practice in 5410 and 5411 (when the currency dropped). Maharshach says that one can be Mezakeh through another. I disagree.

Shulchan Aruch (ibid): If the time did not yet come, if the impending currency change, tax or conscription is evident, Levi cannot force David to accept payment before the time. If there are no such or similar problems, even if David does not want to accept payment, lest he have responsibility until the due date, we do not heed him. Fixing a time is for the borrower's benefit.

SMA (5): Paying in a Midbar even within the time is like when the problem is here at the time of payment. When a problem is imminent, one cannot pay early because the lender could not demand payment, so clearly he pays to avoid the problem. Therefore, it is like paying in the Midbar. We need not say that the currency will change immediately, just that it is imminent.

Prishah (5 DH u'Mah she'Chosav Ein): Because there is great danger in a Midbar, payment there is not considered payment. Some say that when one pays early, we are concerned lest there will be an evident Ones before the time comes, and it is like paying in a Midbar. This is wrong. Sefer ha'Terumos considers paying early like paying on time because the time was fixed for the borrower's benefit.

Bach (1 DH v'Im): Why couldn't the Gemara explain like it initially thought, that the Beraisa teaches that the borrower can return Bal Korcho of the lender? We can say that the Mishnah says that he cannot do so before the loan is due! Perhaps the Gemara assumes that the Mishnah and Beraisa discuss Stam loans, since they did not specify. Even though a Stam loan is for 30 days, a borrower is believed to say that he paid within 30 days (Rosh Bava Basra 1:9). Sefer ha'Terumos discusses these laws in two Simanim. In the first, he distinguishes only between the Yishuv and Midbar. That is when no time for payment was fixed. In the second, he distinguishes only between whether or not the loan was due. That is when a time for payment was fixed.

Shiltei ha'Giborim (Bava Kama 44a 1): If Ploni lent to a storeowner (Moshe) to lend to a Nochri with Ribis, and Ploni gets a share of the Ribis, it is to his detriment to get his money back early, so he can prevent Moshe from returning it before the time.

Bach (5 DH u'Mah): If the problems were known at the time of the loan, the date was for the benefit of the lender, so the borrower cannot force him to accept payment early. This is even if the problem passed, and the borrower merely wants to escape responsibility, and the chance of loss is small. Tosfos (Gitin 75a DH Michlal) says that (regarding Bayis Ir Chomah, even after the time came) payment Bal Korcho is invalid if the receiver loses. Shiltei ha'Giborim says that one cannot force the lender to accept early payment if this will limit his gain, all the more so if it will cause him a loss!

Rebuttal (Shach 11): If the problem passed, the lender cannot refuse to accept payment. We cannot learn from Bayis Ir Chomah, in which there is a loss now. We cannot learn from the storeowner (in Shiltei ha'Giborim), for that loan was made in order that the lender will profit.

Tumim (6): The Rosh (Gitin 6:7) and Rashba distinguish a loan from Bayis Ir Chomah. The latter is a new sale. Also, a borrower can say 'I hold like Version #2 of Rava, that payment Bal Korcho is valid.' Why do the Bach and Shach agree about the storeowner? There are places that allow early return of Mashkanta, even though the lender ate much Peros for a small amount, and now loses this! Likewise, a worker can end an Iska (a half-loan, half deposit in which the investor pays a wage to the worker and gets profits) before the time! The Rashba (Kidushin 13a DH Savra) says that a Shomer can return the deposit early, just like a worker can quit in the middle, for Bnei Yisrael are slaves only to Hash-m. The same applies to the storeowner.

Ketzos ha'Choshen (74:1): The Ra'avad and Magid Mishneh hold that a Shomer cannot return the deposit early, for Shmirah is unlike a job. It is acceptance of liability for loss to the deposit. One can retract early from working for an Iska, but not from responsibility to guard it. Likewise, the storeowner cannot exempt himself from guarding the money for the set time.

Gra (10): In Makos, we obligate witnesses for trying to make one pay a loan early. This implies that (barring special problems) it is always considered advantageous for the borrower to delay payment.