Gemara

27b (Rav Chisda): The custom is, one who kicks someone with his knee must pay three Sela'im. For kicking with the foot, he pays five Sela'im...

86a (Mishnah): We evaluate embarrassment according to the one who embarrassed and the one who was embarrassed.

(Beraisa - R. Meir): Rich and poor people (who were embarrassed) are judged equally, as if they were rich people who lost their property, for all descend from Avraham, Yitzchak and Yakov.

R. Yehudah says, a rich person is judged according to his wealth. A poor person is judged according to his poverty;

R. Shimon says, a rich person is judged like a rich person who lost his property. A poor person is judged like the poorest man there is.

Our Mishnah is unlike R. Meir, who judges rich and poor equally. It is unlike R. Yehudah, for the (Seifa (86b) of the) Mishnah obligates one who embarrasses a blind person, and R. Yehudah exempts. Rather, it is like R. Shimon.

90a (Mishnah): If one was Toke'a a man (hit him near the ear; others explain, blew a Shofar in his ear), he pays one Sela;

R. Yehudah says, he pays a Maneh (100 Zuz).

One pays 400 Zuz if he slapped someone with the back of the hand, tugged on his ear... the rule is, the payment is according to his prestige.

R. Akiva says, we view even the poorest Bnei Yisrael as if they were rich people who lost their money, for they descend from Avraham, Yitzchak and Yakov.

A case occurred in which Levi was Toke'a David. R. Yehudah Nesi'ah obligated him to pay a Maneh Tzuri (of pure silver).

36b: A case of Toke'a occurred, and Rav Tuvya bar Masnah asked if the Mishnah means a Sela Tzuri, or a common Sela (seven eighths copper). Rav Yosef answered that it is the latter. Rav Huna ruled similarly in another case.

91a - Question: The first Tana says that he pays according to his prestige. Is this a leniency (400 Zuz is only for the most distinguished people), or a stringency (400 is for the lowliest people)?

Answer: R. Akiva says that we view even the poorest Yisrael like a rich person who lost his money. This implies that the first Tana teaches a leniency.

Rishonim

Rif and Rosh (30b and 8:7): We evaluate embarrassment according to the one who embarrassed and the one who was embarrassed.

Rosh: We established the Mishnah like R. Shimon. This connotes the Halachah follows R. Shimon. Why did the Rif omit this? It seems that he relies on what he wrote later (see (3) below), that the first Tana views a rich person like a rich person who lost his property, and the Shi'ur is 400, like R. Shimon.

Rebuttal (Gra CM 420:31): The rule is, the Halachah follows R. Yehudah against R. Meir or R. Shimon (Eruvin 46b). The Gemara established the Mishnah like R. Shimon only because it obligates one who embarrassed a blind person. Regarding how much a rich or poor person receives, the connotation of the Mishnah is like R. Yehudah. This is why the Rif did not cite R. Shimon. However, the Rosh's other proof (see (3) below) is solid.

Rif and Rosh (32b and 8:15): The Yerushalmi says that one who embarrasses a Chacham pays the full amount. A man got angry at R. Yehudah bar Chanina, and Reish Lakish fined him a Litra of gold. The payment is according to his prestige. R. Akiva taught that we view even the poorest Bnei Yisrael as if they were rich people who lost their money. This implies that the first Tana teaches a leniency, and less distinguished people receive less than 400.

Rebuttal (Yam Shel Shlomo 8:16): The Rosh misunderstood the Rif. Perhaps the first Tana holds that 400 is for the most esteemed person, and less esteemed people receive less, and it is like R. Yehudah! The Mishnah (85b) says that Boshes is according to the person's honor. R. Yehudah agrees with this, just the Seifa proves that he did not teach the Mishnah. Therefore, we follow R. Yehudah against R. Shimon. No one, even the Tur, is lenient to view a rich person like a rich person who lost his property.

Rambam (Hilchos Chovel u'Mazik 3:1): Embarrassment depends on the one who embarrassed and the one who was embarrassed. Being embarrassed by a lowly person is unlike being embarrassed by a great person. The former is greater.

Question (Lechem Mishneh): The Rosh said that since we established the Mishnah to be like R. Shimon, this connotes the Halachah follows R. Shimon. It seems that the Rambam rules like R. Yehudah. What is his reason?

Note: Perhaps the Rambam holds like the Yam Shel Shlomo above.

Rambam (9): For kicking with the knee, one pays three Sela'im. For Toke'a, one pays a Sela. One pays 400 for slapping with the back of the hand.

Rambam (11): This is for a respected person. A disgraced person who is not particular about such matters receives only what the judges deem proper, for such people are not concerned for their shame. They disgrace themselves through jesting, or in order to get a Perutah from scoffers who jest with them.

Magid Mishneh: The fines in the Mishnah are for a respected person. (A lowly person receives less). The Gemara didn't say to whom Rav Chisda's fines apply. The Rambam says that also they are for dignified people. This is right.

Tosfos (27b DH Harei): Some say that Rav Chisda's fines are for the poorest Oni. The Ri says that they are for the greatest Yisrael, like the fines in the Mishnah (90a), which we say are for the greatest Yisrael (91a).

Rosh (10): To minimize the argument, R. Tam says that the first Tana obligates a Sela for (being Toke'a) an Oni, and R. Yehudah obligates a Maneh for the richest Yisrael. Even though R. Yehudah Nesi'ah obligated him a Maneh for Toke'a, we follow the Amora'im (36b) who obligated only a common Sela.

Poskim

Shulchan Aruch (CM 420:24): Embarrassment is based on the one who embarrassed and the one who was embarrassed. Being embarrassed by a lowly person is unlike being embarrassed by a great person. The former is greater.

Rema: Similarly, the embarrassment of a more dignified person is greater. The embarrassment of a Kohen is greater than that of someone else.

Shulchan Aruch (41): Chachamim fixed an amount for some blows.... For Toke'a, one pays a Sela. For slapping with the back of the hand, he pays 100 Sela'im.

Shulchan Aruch (43): This refers to an honorable person. A lowly person who is not particular about these things receives like the judges deem proper.