Midrash su Salmi 126:5

GEMARA: R. Nachman said to R. Isaac: "Does the first rain then descend in the month of Nissan? Behold, it descends in Mar-Cheshvan, for we have been taught in a Baraitha: 'The first rains fall in Mar-Cheshvan and the latter rains in Nissan.'" Whereupon R. Isaac answered, thus said R. Jochanan: The above passage refers only to the time Joel, son of Pethuel, where it is written (Joel 1, 4) That which the palmarworm hath, the locust hath eaten; and that which the locust hath left, the canker-worm hath eaten. In that year the month of Adar had already been passed, and the first rain descended in the month of Nissan. When the prophet said to Israel: Go and sow your seed, and they replied: "Should one who has a kab or two of barley or wheat eat it and live, or should he sow it and die [e'er the new grain become ripe]?" And he said to them: "Nevertheless, see that ye sow as much as ye can." Thereupon a miracle occurred, that the grain which had been hidden in the walls and in the cracks, as well as in the eaves hidden by the ants, was discovered. They then went and sowed their grain on the second, third, and fourth days of Nissan. On the fifth of Nissan the second rain fell, and on the sixteenth of that month they already offered up the Omar, which had ripened. It was thus found that the grain which should have taken six months to ripen matured in eleven days; and the Omar of grain, usually six mouths in growing, was then brought of such as had been only eleven days in growing; concerning this generation Scripture says (Ps. 126, 5) Those that sow in tears shall reap in joyful song.