Reference for Taanit 37:15
וכן שפסקו גשמים בין גשם לגשם כו': מאי מכת בצורת אמר רב יהודה אמר רב מכה המביאה לידי בצורת אמר רב נחמן נהרא אנהרא
R'ELIEZER SAYS: IF BEFORE NOON THEY DO NOT COMPLETE THE FAST, AFTER NOON THEY DO COMPLETE IT. IT HAPPENED THAT THE RABBIS ORDAINED A FAST IN LYDIA AND RAIN FELL BEFORE NOON. THEREUPON R'TARFON SAID TO THEM: GO, EAT AND DRINK AND OBSERVE THE DAY AS A HOLIDAY. THEY WENT AND ATE AND DRANK AND OBSERVED THE DAY AS A HOLIDAY AND AT EVENING TIME THEY CAME AND RECITED THE GREAT HALLEL.<span class="x" onmousemove="('comment',' Ps. CXXXVI. Cf. Ber. 4b.');"><sup>7</sup></span> <big><b>GEMARA: </b></big>THE ORDER OF PUBLIC FASTS AFOREMENTIONED IS OBSERVED ONLY IN CONNECTION WITH [THE WITHHOLDING] OF THE FIRST RAIN. A contradiction was raised against this Mishnah: [If rain is withheld at the time of] the first and second rainfalls prayers are offered; if at the thir rainfall, fasts are observed!<span class="x" onmousemove="('comment',' Here it is stated that fasts are ordained after these three rainfalls had failed, whereas the Mishnah says that the fasts are observed immediately after the first expected rainfalls had failed. vbuatr vghcr vruh');"><sup>8</sup></span> Rab Judah replied: The Mishnah means this: The order of fasts aforementioned is observed only when the time for the first, second and third fructification rainfalls has passed and no rain fell, but if rain fell at the time for the first fructification rainfall and they sowed but nothing sprouted for or if the [plants] did sprout forth but they had undergone an unusual change the alarm is sounded at once.<span class="x" onmousemove="('comment',' The phrase does not denote, as it was assumed, the first fructification rain but the whole of the former rain season () which comprises three fructification rains as stated supra 6a.');"><sup>9</sup></span> R'Nahman said: Only when they had undergone an unusual change, but not if they merely withered away. Is not this self-evident? We clearly learned, HAVE UNDERGONE A CHANGE[R'Nahman's statement] is needed to cover the case of seeds that have already shot up into stalks. You might have thought that this is a sign of recovery, he therefore informs us [that it is not]. THE SAME TOO IS DONE IF FORTY DAYS ELAPSED BETWEEN THE FIRST AND THE SECOND RAINFALLS AND NO RAIN FELL etc. What is the nature of the plague of drought? Rab Judah said in the name of Rab: A plague which leads to scarcity. R'Nahman said: When [grain] has to be transported by river