Gemara

60b (Rav Huna): Plishtim were hiding in stacks of Yisrael. David asked whether he may use others' money to save himself. The Sanhedrin answered that a commoner may not, but a king may break down walls to make a path for himself.

61a: "David did not want to drink", i.e. to rely on the special right of a king.

117a: Nochrim forced Reuven, and he showed them Shimon's money. Rav Huna bar Yehudah obligated Reuven to pay. Rava told him to retract the ruling.

(Beraisa): If Nochrim forced Reuven, and he showed them Shimon's money, he is exempt. If Reuven took the money and gave it to them, he is liable.

(Rabah): If he voluntarily showed them, this is like taking the money and giving it to them.

Nochrim forced Ploni to show them money. He showed them Rav Mari's wine. They asked Ploni to help them carry it; he complied. Rav Ashi exempted him.

Question (Rabanan - Beraisa): If Reuven took the money and gave it to them, he is liable.

Answer (Rav Ashi): That is when Reuven brought the money to them. Here, he helped them only after they already saw it. It is as if they already took it.

Question (R. Avahu - Beraisa): If an Anas (extortionist) told Reuven 'pass to me a bundle of sheaves or a cluster of grapes', and he passed it to him, he is liable.

Answer (Rav Ashi): The case is, the Anas was on the other side of a river. He could not have taken it himself.

Support: He said 'pass to me', not 'give to me'.

117b: Reuven had deposited a silver cup by Shimon. Robbers came; he gave it to them. Rabah exempted him.

Objection (Abaye): He saved himself with another's money!

(Rav Ashi): If Shimon is wealthy, presumably, the robbers came for his money. If Shimon is not wealthy, the robbers came for Reuven's cup, so Shimon is exempt.

Sanhedrin 74a (Rava): If Levi was Rodef Ploni and Ploni broke someone else's Kelim, he is liable. One may not save himself with another's money.

Rishonim

Rif (43a): Showing due to Ones is exempt, for it is Gerama. Bringing is an overt action. A Beraisa teaches that if an Anas told Reuven to pass a bundle, and he did, he is liable, i.e. when the Anas could not have taken it himself.

Nimukei Yosef: All agree that if an Anas asked to bring Ploni's money, the Moser is exempt. If so, why did we need to say that a deposit is different, because the Shomer is like the owner's hand? Rather, we exempt only when the money is in Ploni's Reshus. Then, we say that the Anas came for Ploni's money.

Chidushei Anshei Shem (1): We must say that the cup was not in his Reshus, therefore we needed to say that the Shomer is like the owner's hand.

Rosh (10:27): If one was not coerced and he showed others' money to Nochrim, he is liable. If he was coerced, he is exempt. This is even if after showing he carried it for them, for once he showed it, it is as if was already burned. If he was coerced to bring money from Ploni's house, he is liable.

Mar'eh ha'Panim (Yerushalmi Bava Kama 37a DH Aval): The Yerushalmi exempts even when the Nochri designated which money the Yisrael must bring. The Ramban says that the Yerushalmi discusses a deposit. Ploni is exempt when the Anas came for the deposit. This is the Rosh's intent.

Rambam (Hilchos Chovel u'Mazik 8:3): If the king commanded to bring wine or straw, and a Moser got up and said 'Ploni has a storehouse of wine or straw in such and such place, he is liable. If the king forced the Moser until he showed storehouses of wine or straw, or until he showed the money of Ploni who was fleeing the king, he is exempt, for if he does not show, they will beat or kill him.

Yam Shel Shlomo (10:47): If one was coerced to show money of Yisrael, he should show his own. If he showed another's, he save himself with another's money, and he is liable. If he was coerced to show storehouse of wine and oil, and he does not have, he need not offer his money in place of showing another's. This is why the Rambam says about money that he was asked to show 'Ploni's, but does not say 'Ploni's storehouse.' The Ones is to show the smallest storehouse. If he shows David's, rather than the smaller storehouse of his friend Levi, he pays David the excess of David's over Levi's. This is like one who can save by destroying a limb. He is liable if he kills. A Shomer who was coerced to be Moser is exempt, for he is exempt for Ones. A Moser is only Gerama, so he is exempt if he was coerced. However, if he picked up the item he acquired it to be liable for it.

Rambam (4): If one took the money and handed it to the Anas, he is liable in any case, even if the king forced him to bring. We say that one who was forced to bring is liable for bringing when the property did not reach the Anas's Reshus. If an Anas forced a Yisrael until he showed, and stood by the money and it became in his Reshus and forced a Yisrael to take it elsewhere, even if it is the same Yisrael who showed them, he is exempt. Once the Anas stood by the storehouse, everything in it is lost, as if it was burned.

Magid Mishneh: The Rashba (in his Chidushim) agreed, and added that one who was forced to bring is liable only if the Nochri could not have taken it himself. Even if the Nochri does not see the money, if he has control over the area and can search and find it, the Yisrael is exempt.

Poskim

Shulchan Aruch (CM 388:3): If the king forced the Moser until he showed to him the money of Ploni who was fleeing the king, he is exempt, for if he does not show, they will beat or kill him.

SMA (9): This is not only if Ploni fled. It is merely a normal case. Had he not fled, it would be unusual for Anasim to force Levi to show Ploni's money.

SMA (11): If Ploni had no money and they forced Levi to show Ploni for them to seize until the congregation or his relatives will redeem him, if Levi could have exempted himself from the Anas by giving the same amount of money, he may not cause damage to the congregation or Ploni's relatives.

SMA (12): The Rambam and Shulchan Aruch say 'he is exempt.' This connotes that l'Chatchilah, he should not show.

Shulchan Aruch (4): If one took the money and handed it to the Anas, he is liable in any case, even if the king forced him to bring.

SMA (13): This is unlike thieves who took a deposit from a Shomer who is not assumed to be wealthy (292:8). There, we assume that they came for the deposit. Here, we must say that the Moser's bad Mazel caused the Anas to force him to bring money not in his Reshus.

Shulchan Aruch (ibid.): One who was forced to bring is liable for bringing when the property did not reach the Anas's Reshus (Rema - i.e. he has control over it and can take it). If an Anas forced a Yisrael until he showed, and stood by the money and it became in his Reshus, and he forced a Yisrael to take it elsewhere, even if it is the same Yisrael who showed them, he is exempt. Once the Anas stood by the storehouse, everything in it is lost, as if it was burned.