Gemara

Kesuvos 67b (Beraisa): "Sufficient for what he lacks" - you are commanded to finance him. You need not make him wealthy. "That is lacking to him" - even a horse to ride on, and a slave to run in front of him;

There was a poor man that was born to a rich family. Hillel bought for him a horse to ride on and a slave to run in front of him. Once, he did not find a slave to run in front of him; Hillel ran three Mil (about three kilometers) in front of him.

(Beraisa): A case occurred in the Galil, in which a man from a rich family became poor. They bought for him one Litra of fowl (which is expensive) each day.

Some say that each day they bought for him meat with a Litra of coins. Some say that he lived in a small village, and they slaughtered an animal for him each day (even though much of the remaining meat would be wasted).

A man came in front of R. Nechemyah and requested food. He said that he normally eats fat meat and old wine.

R. Nechemyah had lentils. He offered the man to eat with him. The man ate some of the lentils and died. R. Nechemyah was not concerned that he killed him. The man was at fault for making himself so finicky.

A man came in front of Rava and requested food. He said that normally ate fattened hens and old wine.

Rava: You should be concerned for imposing on the money of the congregation!

The man: Do I eat from them?! I eat from Hash-m!

(Beraisa): "The eyes of all hope to You, and You give to them their food in his time" - it does not say in their time, rather in his time, teaching that Hash-m gives each one his food in his time.

In the meantime, Rava's sister came. He had not seen her for 13 years. She brought with her a fatted hen and old wine. He invited the man to eat.

Mar Ukva used to give 400 Zuz to a particular Oni every Erev Yom Kipur. Once, he sent the money with his son. His son said that the man does not need the money, for he saw them scenting the house by sprinkling old wine on the floor.

Mar Ukva realized that they were very delicate, so he sent double the amount he used to send.

R. Chanina used to give four Zuz to a certain man every Erev Shabbos. Once, he sent the money with his wife. His wife said that he does not need the money, for she heard them saying 'on what should we dine today, on linen cloths, or colored silk cloths?' R. Chanina agreed that the man is a swindler.

Shabbos 118a (Mishnah): One who has food for two meals may not take from the Tamchuy (food distributed daily to the poor). One who has food for 14 meals may not take from the Kupah (money distributed weekly).

Question: Everyone requires eating at least three meals on Shabbos! (The limit for taking from the Kupah should be 15 meals.)

Answer #1: The Mishnah is like Chachamim, who say that one eats three meals on Shabbos. He does not eat on Motza'ei Shabbos.

Answer #2: The Mishnah is like R. Akiva, who says that it is better to conduct on Shabbos like on a weekday (and have only two meals) than to receive Tzedakah.

Pesachim 112b (Tana d'Vei Eliyahu): Even though R. Akiva taught that it is better to conduct on Shabbos like on a weekday than to take from others, even an Oni should prepare a small matter to honor Shabbos.

(Rav Papa): This 'small matter' is Kasa d'Harsena (fish fried in its oil with flour).

Rishonim

Rambam (Hilchos Shabbos 30:7): One should make Shabbos like a weekday rather than to take from others.

Rif and Rosh (Kesuvos 29a and 6:8): We give to an Oni "what is lacking to him" - even a horse to ride on, and a slave to run in front of him. There was a poor man born to a rich family, and Hillel bought a horse for him to ride on and a slave to run in front of him.

Shitah Mekubetzes (67b DH Afilu): The Ge'onim say that this is only if people do not know that he lost his wealth. If it is known, he is like any other Oni.

Rambam (Hilchos Matanos Aniyim 7:3): We are commanded to give to an Oni according to what he lacks. If he lacks clothing, we cover him. If he lacks Kelim for the house, we buy them for him. If he lacks a spouse, we marry him off. Even if the Oni was used to riding on a horse with a slave running in front of him before he became poor, we buy a horse and a slave for him, for it says "what is lacking to him." You must fill his lack. You need not make him rich.

Ri Korkus: One might have thought that if one was used to wealth, this is a need, just like a horse and a slave. 'That is lacking' teaches that this is not so.

Rambam (10:18): One should force himself to bear pain to avoid taking from people and casting himself on the Tzibur. One should make his Shabbos Chol rather than take Tzedakah. Even if a Chacham or distinguished person became poor, he should engage in menial labor to avoid taking Tzedakah.

Tosfos (68a DH bi'Talei): When R. Chanina heard that the family dined on linen and silk tablecloths, he did not send more money. This is unlike sprinkling wine, for one cannot be finicky about this.

Poskim

Shulchan Aruch (OC 242): 'Make Shabbos Chol rather than take Tzedakah' applies only if one is very pressed.

Magen Avraham (2): This refers to one who has enough only for two meals each day. He does the same on Shabbos and does not take Tzedakah.

Taz (1): One who has money should economize on weekdays to avoid becoming poor, but he should not economize regarding Shabbos. If one is partially dependent on others, he honors Shabbos modestly, i.e. three meals and Kasa d'Harsena. If one is totally dependent on others, he is exempt from honoring Shabbos, and eats two meals like on Chol.

Mishnah Berurah (1): If one needs to take Tzedakah, the Gabayim must give to him at least three meals and Kasa d'Harsena. They give more to an honorable person, according to his honor.

Shulchan Aruch (YD 250:1): We give to an Oni what he lacks. If he is hungry, we feed him. If he lacks clothing, we cover him. If he lacks Kelim for the house, we buy them for him. Even if the Oni was used to riding on a horse with a slave running in front of him before he became poor, we buy a horse and a slave for him. We give to everyone what is appropriate for him, be it hot or cold bread, dough or a bed.

Source #1 (Gra 1): We find that Chachamim asked Aniyim what they normally eat (Kesuvos 67b).

Source #2 (Sifri on Devarim 15:11): The verse discusses giving to "your brother, your Aniyim, and Evyonecha (your destitute)" to teach that we to everyone what is appropriate for him: bread, dough, a Mo'oh (32 Prutos). If one must put the food in his mouth, we do so.

Bach (DH Tanya): This means that if he is not satisfied with bread or dough, we give him a Mo'oh to buy food he desires.

Malbim (on Sifri): The Sifri teaches that we give to everyone according to his honor. To your brother you give dough and a Mo'oh (or Mitah (bed), according to the Shulchan Aruch's text). To an Oni you give bread. You put the food in the mouth of an Evyon.

Shulchan Aruch (ibid.): If he must be fed, we feed him. If he is single and comes to marry, we marry him off. We rent a house for him, spread a bed and necessary Kelim, and afterwards we marry him off.

Source (Tosefta Pe'ah 4:10): If an Oni used to use silk Kelim, we give to him silk. If he must be fed, we put the food in his mouth. "Lo" teaches that we marry him off - "E'eseh Lo Ezer k'Negdo."

Shulchan Aruch (255:1): One should force himself to bear pain to avoid taking from people and casting himself on the Tzibur. One should make his Shabbos Chol rather than take Tzedakah. Even if a Chacham or distinguished person became poor, he should engage in menial labor to avoid taking Tzedakah.