Gemara

48b (Mishnah): A debt is not collected from Meshubadim (i.e. property that was sold to someone else) if the debtor has Bnei Chorin (property that he did not sell), even if it is Ziburis (lowest quality land). This is an enactment for Tikun ha'Olam.

50b - Question (Rav Achdevoy bar Ami): Is a gift considered Meshubadim?

If the enactment was lest buyers lose, if a creditor collects land given for a gift, the receiver did not lose, so no enactment was made. Or, do we say that surely the receiver benefited the giver, so losing a gift is like a loss?

Answer (Mar Kashisha brei d'Rav Chisda - Beraisa): If a Shechiv Mera (one who fears lest he die from his illness) said 'give 200 Zuz to Reuven, 300 to Shimon, and 400 to Levi', precedence of document does not give precedence for collection. Therefore, if a loan document is collected from them, it is collected from all of them.

If he said 'give 200 Zuz to Reuven, and after him to Shimon, and after him to Levi', precedence of document gives precedence for collection. Therefore, if a loan document is collected from the estate, it is collected from the last recipient. If he did not receive enough to pay it, the rest is collected from the previous recipient... Even if the first recipient received Beinonis, and the last received Ziburis, the loan is collected from the Ziburis (for this was the borrower's last Bnei Chorin).

This shows that the enactment was made also regarding recipients of gifts!

Rejection #1: No. The case is, Reuven, Shimon and Levi did not get gifts. They were creditors being paid up!

Even though the Beraisa says 'give', it means 'give the money that I owe.'

In the Seifa, they collect in order. If the creditors had documents, the earliest document would be paid first! The case is, the creditors have no documents.

The Beraisa mentions precedence of document, i.e. whoever is mentioned first in the document detailing the command of the Shechiv Mera.

Rejection #2: Really, a creditor takes Beinonis no matter who received it. The Beraisa discusses taking from the last one, for he always suffers the loss. (If a recipient or buyer loses land, he is compensated by later recipients.)

Rejection #3: In the Beraisa, all the lands are the same quality. (If they were not, the creditor would collect Beinonis, even if it the last recipient did not have it!)

Rishonim

Rif (Bava Basra 64a): The Beraisa taught that a loan document is collected from them, i.e. from each according to what he received. We follow the intent of the giver. He wanted Levi to receive a third more than Shimon, and twice as much as Reuven, and that Shimon receive a half more than Reuven. Likewise, if the Shechiv Mera did not leave enough property for all the gifts, they receive according to this calculation.

Rambam (Hilchos Zechiyah 10:13): If a Shechiv Mera said 'give 200 Zuz to Reuven, 300 to Shimon, and 400 to Levi, precedence in the document does not give precedence for collection. Therefore, if he left less than 900 Zuz, they divide what he left according to what he wrote to them. A loan document against them is collected from each of them according to what he received. E.g. if the debt was 450, Reuven pays 100, Shimon pays 150, and Levi pays 200.

Rambam (14): However, if he said 'give 200 Zuz to Reuven, and after him to Shimon, and after him to Levi', precedence in the document gives precedence for collection. Therefore, a loan against them is collected from the last recipient. If he did not receive enough to pay it, the rest is collected from the previous recipient.

Rosh (Bava Basra 8:52): There is no precedence among the recipients only when he gave different amounts. If he gave the same to each, even without Acharayos, since he could have said 'give 200 to each of these' or 'give to the three of them 600' (but did not), this shows that he wanted to give to them in this order.

Question: If so, why did the Beraisa distinguish between when he did and did not say 'and after him...'? It should discuss when he did not say 'and after him...', and distinguish between when the gifts were equal and when they were different!

Answer (Rosh, citing Rashbam DH Giveh): The Beraisa teaches the Chidush that (when he said 'and after him...'), even though he likes the last recipient most and gave to him the biggest gift, the loan is collected from him.

Rebuttal (Magid Mishneh 13): The Meforshim agreed that whenever he did not say 'and after him...', they are equal (no one has precedence).

Rosh (ibid.): In the Reisha, when he collects form all of them, he collects two ninths from the first, three ninths from the second, and four ninths from the last.

Tosfos (Gitin 50b DH Goveh): It seems that the debt is collected from each according to what he received. R. Chananel equates the law to three Kesuvos collected from one man. It seems that it is different.

Poskim

Shulchan Aruch (CM 111:8 and 253:9): If Moshe gave gifts, and wrote 200 to Reuven, 300 to Shimon, and 400 to Levi, and there is not enough property for all of them, precedence in the document does not give precedence for collection. Rather, we divide the property into nine parts. Reuven gets two parts, Shimon gets three, and Levi gets four. If a loan document is collected from them, each of them pays according to what he received.

SMA (16,17): It is also a Chidush that even though he likes Levi most, the loan is collected equally from all of them. We assume that he wanted them to collect equally, just one cannot say different things at the same time.

SMA (18): This is unlike three creditors collecting from one borrower. They all collect equally, even if some are owed more. There, the property was Meshubad equally to all of them. Here, we follow the giver's intent. He wanted to give more to Levi, according to this ratio.

Shulchan Aruch (ibid.): However, if Moshe said 'give 200 to Reuven, and after him 300 to Shimon, and after him 400 to Levi', precedence in the document gives precedence for collection. Therefore, if a loan document is collected from the estate, it is collected from Levi. If he did not receive enough to pay it, the rest is collected from Shimon. If this is not enough, the rest is collected from Reuven.

Beis Yosef (DH Lefichach): The Rashbam (Bava Basra 138a DH Tanu) says that the Beraisa discusses a Shechiv Mera because a healthy person normally gives to each recipient individually, and we would know the order in which he gave.

Shulchan Aruch (253:9): If a Shechiv Mera said 'give 200 to Reuven, 300 to Shimon, and 400 to Levi, precedence in the document does not give precedence for collection (Rema - he did not pause in the middle, which would show retraction). Therefore, we divide the property according to what he gave. A loan document against them is collected proportionally according to what each one received. However, if he said 'give 200 to Reuven, and after him 300 to Shimon, and after him 400 to Levi', precedence in the document gives precedence.

Beis Yosef (DH Shechiv): The loan is collected if they received land, or if it was collected before the recipients collected. (If the recipients already collected money, the creditor does not collect form them.)

Rema: Some say that the same applies if he said 'give 200 to Reuven, and 200 to Shimon, and 200 to Levi.' Since he gives the same amount to each, but did not give together, it is as if he said 'and after him, give...' Some disagree.

Beis Yosef (DH v'Chosav ha'Rosh): The Nimukei Yosef says that even if one of them seized Metaltelim, we force him to return them.

Shulchan Aruch (ibid.): Therefore, if a loan document is collected from the estate, it is collected from Levi. If he did not receive enough to pay it, the rest is collected from Shimon. If this is not enough, the rest is collected from Reuven.