וְהָאָ֗רֶץ אֲשֶׁ֨ר אַתֶּ֜ם עֹבְרִ֥ים שָׁ֙מָּה֙ לְרִשְׁתָּ֔הּ אֶ֥רֶץ הָרִ֖ים וּבְקָעֹ֑ת לִמְטַ֥ר הַשָּׁמַ֖יִם תִּשְׁתֶּה־מָּֽיִם׃
너희가 건너가서 얻을 땅은 산과 골짜기가 있어서 하늘에서 내리는 비를 흡수하는 땅이요
Sefer HaMiddot
4. Recital of Tehillim (Psalms) is a segulahfor rainfall. [The letters of the word] Tehillim [are the acronym for the Biblical phrase] -- "According to the Rains of the Heavens, You will drink Water."
Sefer HaMiddot
7. The saying of Tehilim (Psalms) is conducive (segula) to causing rain to fall. [This is learned from the Hebrew letters of the word] TeHiLiM= Limtar''H'ashamayim'T'ishteh'M'ayim (Deutronomy 11:11 "According to the rain from heaven, you will drink water.")