וְעַל־הַנַּ֣חַל יַעֲלֶ֣ה עַל־שְׂפָת֣וֹ מִזֶּ֣ה ׀ וּמִזֶּ֣ה ׀ כָּל־עֵֽץ־מַ֠אֲכָל לֹא־יִבּ֨וֹל עָלֵ֜הוּ וְלֹֽא־יִתֹּ֣ם פִּרְי֗וֹ לָֽחֳדָשָׁיו֙ יְבַכֵּ֔ר כִּ֣י מֵימָ֔יו מִן־הַמִּקְדָּ֖שׁ הֵ֣מָּה יֽוֹצְאִ֑ים והיו [וְהָיָ֤ה] פִרְיוֹ֙ לְמַֽאֲכָ֔ל וְעָלֵ֖הוּ לִתְרוּפָֽה׃ (ס)
And by the river upon the bank thereof, on this side and on that side, shall grow every tree for food, whose leaf shall not wither, neither shall the fruit thereof fail; it shall bring forth new fruit every month, because the waters thereof issue out of the sanctuary; and the fruit thereof shall be for food, and the leaf thereof for healing.’ .
Tosefta Ta'anit
We ask for the rains until Nissan is over, as it says, "And rain will fall for you, the earlier and latter rains during the first [month] (Yoel 2);" [these are] the words of Rabbi Meir. And the Sages say,"Earlier rains [fall in] Marcheshvan, and latter rains [fall on] the first of Nissan (and so these dates are the timetable for prayers for rain). Rabbi Meir said to them, "Knowing that a tree makes fruit for twelve [months], and produce [grows] for six months; what have we found with trees, as it says [about it], "By its month (meaning halfway through the month), it will bear (Yechezkel 47)," so too produce, at its fifteenth day [its season ends]. Haven't you learnt, that earlier and latter rains [fall throughout] Nissan.