cellio | daf bit: Ta'anit 15

At the end of Sukkot we begin to pray for rain. If a few weeks pass and we get to the 17th of Cheshvan without rain, the rabbis (according to the mishna) would call for three communal fasts. If the month of Kislev arrives and there's still no rain, there are three more fasts. If that passes (it doesn't specify a deadline this time) there are three more. Each of these sets is more demanding than the previous.

The g'mara has been discussing this for a few pages. During these fasts people would rend their garments (like in mourning) and fall on their faces in prayer. The g'mara discusses the efficacy of these practices.

R. Eleazar said: not everyone is answered through rending his garments or through falling on his face. Further, he said, in the messianic era not all will rise¹ nor will all prostrate themselves; kings will rise and princes will prostrate. (R. Ze'ira objects, saying that princes will do both.) R. Nachman b. Yitzchak then declared: not all are destined to share in the light nor all in the gladness, as it is written: light is sown for the righteous, and gladness for the upright. (The implication is that "the righteous" and "the upright" might be two different groups, though I presume they would overlap.) (14b-15a)

¹ I'm not sure what he means by "rise" here; from context I don't think he's talking about resurrection of the dead, as that would seem to be a prerequisite for prostrating.