Eruvin 40b #1: Shiv'ah refers to the seven days of creation (Rashi - give one of them to your Creator, and rest on Shabbos). Shemoneh refers to the eight days until circumcision ¹ .

Eruvin 40b #2: Shiv'ah are [Rashi - Korbanos Tzibur ² of] the days of Pesach, and Shemoneh are the days of Sukos. "V'Gam" includes Shavu'os, Rosh Hashanah and Yom Kipur.

Rashi: If you already divided your bread and wealth among seven who need Chesed, divide also to eight who come after them. Do not say 'it is enough what I already gave!' If you will not do so now, when will you? (Avos 1:14)

Ibn Ezra: Shiv'ah refers to the six directions (including up and down), and the middle. Shemoneh refers to the days of the week; the eighth day is like the first (it is the same day of the week). I.e. constantly, without ceasing.

Rashbam: Give to many people - to seven, or even to eight.

Ri Kara: Divide your money among several partners, lest it be gathered in one place.

Rid: This explains "send your bread

Rashi: Perhaps later you will need all of them [to whom you gave]. Then, you will be saved via this Tzedakah. Rid - they will give to you [for you gave to them].

Rashi #1 (based on Eruvin 40b): If the Mikdash will be destroyed, you will not offer any more. The first Korbanos will help you.

Rashi #1 (based on Eruvin 40b): You do not know what was decreed during Sukos about rain. The Korbanos will help and nullify the evil decree.

Ibn Ezra: You do not know if you will come to poverty. It says Yihyeh (masculine), even though Ra'ah is feminine, like "Ki Yihyeh Na'arah ¹ Besulah" (Devarim 22:23).

Ri Kara: If your money is gathered in one place, perhaps there will be a decree against that place, and it will perish with them.

Seforno: Honor them, for perhaps their kingship will succeed, in order to ruin the country due to the evil of its residents.

Metzudas David: Perhaps there will be evil in your land, and you will need to go to other lands, and you will need all of them.

Refer to 11:2:1:1*.