Invoking Allah for Rain (Istisqaa)
Bukhari :: Book 2 :: Volume 17 :: Hadith 129
Narrated Anas:
A man came to the Prophet (p.b.u.h) and said, "Livestock are destroyed and the roads are cut off." So Allah's Apostle invoked Allah for rain and it rained from that Friday till the next Friday. The same person came again and said, "Houses have collapsed, roads are cut off, and the livestock are destroyed. Please pray to Allah to withhold the rain." Allah's Apostle (stood up and) said, "O Allah! (Let it rain) on the plateaus, on the hills, in the valleys and over the places where trees grow." So the clouds cleared away from Medina as clothes are taken off .