147 Taanit 3/1-4

(1) This [previously mentioned] order of fasts applies with regard to the first rains [ie., when they do not descend]; but [if] the plants change [from their normal stage of growth] , we cry out upon them immediately. And so too, if there is an interval between rains of forty days, we cry out upon them immediately, since this is a plague of drought.

(2) If rain sufficient for the growth of sprouts and herbage has fallen, but not for the growth of trees; or sufficient for the growth of trees, but inadequate to the growth of herbage; or sufficient for both, but not to fill the wells, cisterns, and caves, an alarm is immediately to be sounded.

(3) And thus if no rain should have fallen over any particular city similar to that which is written (Amos 4:7), "I caused it to rain upon one city, and caused it not to rain upon another city, one piece was rained upon," &c., [the inhabitants of] such a city must fast, and sound an alarm, and those of the circumjacent places shall fast, but not sound. Rabbi Akivah says, "they are to sound, but not to fast."

(4) And thus, when pestilence reigns in a city, or when the [sound] walls fall down, [the inhabitants of] such a city must fast, and sound an alarm: and those of the circumjacent places shall fast, but not sound. Rabbi Akivah says, "they are to sound, but not to fast." What must be considered as a pestilence? When in a city, capable of furnishing five hundred able men, three persons die in three consecutive days, it is a pestilence; less than this is not a pestilence.