Rashi: On a day that you have the ability to do good, be among those who do good.

Ibn Ezra: A Chacham who has an inheritance and money, why should he rejoice in something that will not last, as if they tell him, on a good day, rejoice? Refer to 7:14:2:3.

Rashbam: Receive Hashem's Brachah with Simchah and a good heart.

Ri Kara: If good comes on the generation, benefit with them.

Seforno: Try to acquire eternal perfection, which is absolute good.

Metzudas David: Your Nefesh should delight in the good.

Rav Sadya Gaon: On the day of good and wealth, see the day of evil and lack.

Rashi: When evil comes on the Resha'im, be among those who see - "v'Yatz'u v'Ra'u Shofetecha b'Ikvei ha'Anashim

Chagigah 15a #1: Everything that Hashem created, He created corresponding to it. He created mountains, and He created hills. He created seas, and He created rivers.

Chagigah 15a #2: He created Tzadikim, and He created Resha'im ¹ ; He created Gan Eden, and He created Gehinom ² . Everyone has two portions - one in Gan Eden, and one in Gehinom. If a Tzadik merits, he gets his portion and his colleague's portion in Gan Eden. If a Rasha is liable, he gets his portion and his colleague's portion in Gehinom.

Rashi: Hashem made good and the reward for doing good, opposite evil and its payment.

Rashbam: Also the good that Hashem gave to you, is payment for the Mitzvah that you did. The evil is for your Aveirah.

Ri Kara: This is Hashem's Midah. When He brings punishment on a person, and he repents, He brings good on him.

Rid: Hashem created good opposite evil, and evil opposite good, lest people have claims against Him. Had He created only good, they would say that He cannot do evil. Had He created only evil, they would say that He cannot do good.

R. Avigdor citing Koheles Zuta: "V'Acharei Ken Yatza Achiv" (Bereishis 25:26) - do not say that this one was a Tzadik [from birth], and this one a Rasha. Why did Hashem create Tzadikim and Resha'im? In order that these will atone for these.

R. Avigdor: He created Ashirim opposite Aniyim, to finance them and receive reward; He created the Yetzer Tov opposite the Yetzer ha'Ra, and Gan Eden opposite Gehinom. The Gematriya of "Asah" equals that of 'Zehu Lechaper Zeh b'Zeh' ³ .

Seforno, Metzudas David: Along with not punishing more than is proper, Hashem makes punishments like the sin, Midah k'Neged Midah.

Ibn Ezra, Metzudas David: "Al Divras" is due to, like "Al Davar Asher Lo Kidemu Eschem ba'Lechem uva'Mayim" (Devarim 23:5) and "Al Divrasi Malki Tzedek" (Tehilim 110:4). The Yud at the end of Divrasi is extra, like in "Rabasi va'Goyim Sarasi ba'Medinos" (Eichah 1:1).

Metzudas David: It is lest people have room for complaint; refer to 7:14:5:3.

Rashi: Man cannot find any reason to complain about Hashem's conduct ¹ . Ibn Ezra - this is because Hashem made "Zeh Le'umas Zeh"; the lack is due to the recipient.

Rid: Refer to 7:14:3:6.

Seforno, Metzudas David: Hashem punishes Midah k'Neged Midah, to dispel room for complaint if one would not know why the evil came.