Midrash su Deuteronomio 28:12

TAANITH (Fol. 2) R. Jochanan said: "Three keys (sources of help) are in the hands of the Holy One, praised be He! which are not intrusted to any agent. They are: [The key] for [help in] confinements, for rain, and for the resurrection of the dead. The key for help in confinements, as it is written (Gen. 30, 22) And God hearkened (Ib. b) to her (Rachel) and opened her womb; that for rain, as it is written (Deut. 28, 12) The Lord will open unto thee His good treasure, the heaven, to give the rain of thy land in its season; and that for the resurrection of the dead, as it is written (Ez. 37, 13) And ye shall know that I am the Lord, when I open your graves and when I cause you to come up out of your graves, O my people. In the West (the land of Israel) it was said: "Also the key of a man's support is in the hands of God Himself, as it is written (Ps. 145, 16) Thou openest Thy hand. etc. Why did not R. Jochanan mention this also? Because R. Jochanan may explain that rain includes the means of maintenance.

“Return, return, O Shulamite; return, return, and we will gaze upon you. Why will you gaze at the Shulamite like at a dance of two companies?” (Song of Songs 7:1)
“Return, return, O Shulamite,” Rabbi Shmuel bar Ḥiyya bar Yudan [said] in the name of Rabbi Ḥanina: Four times “return,” is written here, corresponding to the four kingdoms that rule over Israel. Israel comes under their control unscathed and emerges unscathed. “The Shulamite,” a nation in whose midst the eternal One who lives in peace [shalom] moves about; that is what is written: “I have moved about in a tent and a Tabernacle” (II Samuel 7:6).¹God rested His presence in the Tabernacle in the midst of Israel. The Tabernacle resided in four places in the Land of Israel: Gilgal, Shilo, Nov, and Givon, corresponding to the four times “return” is written here, as though the word Shulamite is written with each one (Maharzu, Bereshit Rabba 66:2).
Another matter, “the Shulamite,” a nation to whom [a blessing] concluding with peace is [recited] each day, just as it says: “And grant you peace [shalom]” (Numbers 6:26). Alternatively, “the Shulamite,” the nation that I am destined to settle in an abode of peace; that is what is written: “My people will live in a peaceful abode…” (Isaiah 32:18). Another matter, “the Shulamite,” the nation to whom I extend peace; that is what is written: “Behold, I will extend peace toward it” (Isaiah 66:12).
Rabbi Elazar bar Rabbi Maron said: A nation that completes [mashlemet] the stability of the world, both in this world and in the World to Come. Rabbi Yehoshua of Sikhnin said in the name of Rabbi Levi: A nation that all the good of the word comes only due to its merit. That is what is written: “God will give you from the dew of the heavens, and from the fat of the earth” (Genesis 27:28); “you,” the matter is dependent upon you and your merit, as it is written: “The Lord will open for you His good storehouse” (Deuteronomy 28:12), the matter is dependent upon you and your merit.
Rabbi Shmuel bar Tanḥum and Rabbi Ḥanan, the son of Rabbi Berekhya from Botzra, [said] in the name of Rabbi Yirmeya: The nation that made peace between Me and My world, as had they not accepted My Torah, I would have returned My world to emptiness and disorder, as Huna said in the name of Rabbi Aḥa: It is written: “The earth and all its inhabitants melt away” (Psalms 75:4). Had Israel not stood before Mount Sinai and said: “Everything that the Lord has said, we will perform and we will heed” (Exodus 24:7), the world would have begun to disintegrate. Who buttressed the world? It is I [anokhi], as it is stated: “I [anokhi] set its pillars firm, Selah” (Psalms 75:4); by the merit of: “I [anokhi] am the Lord your God” (Exodus 20:2), I set its pillars firm.²God caused the pillars of the world to be firm in the merit of the people of Israel accepting the Ten Commandments, the first of which was “I am the Lord your God” (Etz Yosef).

R. Isaac said: "Even in a year of drought, as were the years of Elijah, if rain fall on the Sabbath eve, it can only be considered as a sign of calamity." This significance [is attached to the occurrence also by] Rabba b. Shila, who said: "A rainy day is hard as the day of judgment [because it prevents people from pursuing their vocations]," Amemar said: "Had it not been for its necessity to the world, I would pray His mercy to abolish it." Further R. Isaac said: "Sunshine on the Sabbath is a generosity for the poor; as it is said (Malachi 3, 20) But, there shall be rise unto you that fear my name the sun of righteousness with healing in its wings." Again said R. Isaac: "Great is the day of rain, for then even the coin in one's pocket is blessed; for it is said (Deut. 28, 12) To give the rain of thy land in its season, and to bless all the work of thy hand." R. Isaac said again: "Heavenly blessing does not occur but in things which are hidden from the eyesight [the exact quantity of which is not known]; as it is said (Deut. 28, 8) The Lord will command upon thee the blessing in thy storehouses [where the exact quantity is unknown]." In the college of R. Ishmael it was taught: "Heavenly blessings will not be frequent except upon things of which no eye can look." Our Rabbis were taught: "He who is about to measure the grain in his barn, should say: 'May it be Thy will, O Lord, our God, that Thou shalt send blessing to the labor of our hands.' When he begins to measure off, he should say: 'Praised be He Who sendeth blessings upon this heap.' If, however, he prayed after measuring, his prayer is in vain, because [heavenly] blessing is not frequent on things which are weighed, measured or counted, but on things which are hidden from the eyesight; as it is said: The Lord will command upon thee the blessing in they storehouses [where the exact quantity is unknown]."