A new tractate! Speaking of fast as prayer, specifically when the Land of Israel needs rain. The mishnah opens with the question if defining the rainy season - namely, when do we start praying for rain? Too early, and it's a sign of a curse over Sukkot. So the distinction becomes between asking for rain and mentioning the fact that God is the One who provides rain. Also, where we mention God's role in bringing rain in the Amidah. Note the connection to Berakhot. Plus, God's role in rain, in life, and livelihood.