Mustadrak al-Hakim — Hadith 1240

Hisham bin Urwah narrates from his father, from Sayyidah Aishah (may Allah be pleased with her), who said: The people complained to the Messenger of Allah (peace and blessings be upon him) about the lack of rain, so he (peace and blessings be upon him) ordered a pulpit, which was placed for him (peace and blessings be upon him) at the prayer ground, and he (peace and blessings be upon him) appointed a day for the people on which they would all go out. Sayyidah Aishah (may Allah be pleased with her) said: The Messenger of Allah (peace and blessings be upon him) went out when the edge of the sun appeared. He (peace and blessings be upon him) sat on the pulpit, proclaimed the greatness of Allah and praised Him, and then said: "You have complained of the drought of your lands and the delay of the rain from its appointed time, and Allah has commanded you to call upon Him and has promised you that He will answer you." Then he (peace and blessings be upon him) supplicated: "All praise is for Allah, Lord of all the worlds, the Most Gracious, the Most Merciful, Master of the Day of Judgement. There is no god but Allah; He does what He wills. O Allah, You are Allah, there is no god but You. You are the Self-Sufficient and we are the needy. Send down rain upon us, and make what You send down a source of strength for us and a means of sustenance for a time." Then he (peace and blessings be upon him) raised his hands and kept them raised for so long that the whiteness of his (peace and blessings be upon him) armpits began to show. Then he (peace and blessings be upon him) turned his back to the people and turned his cloak over while still raising his hands. Then he (peace and blessings be upon him) faced the people, came down and led two rak'ahs of prayer. Then Allah Almighty produced clouds with thunder and lightning, and then rain fell by the command of Allah, and he (peace and blessings be upon him) had not yet reached his mosque when the streams began to flow. When he (peace and blessings be upon him) saw the people hurrying toward shelter, he (peace and blessings be upon him) laughed until his (peace and blessings be upon him) molar teeth became visible. Then he (peace and blessings be upon him) said: "I bear witness that Allah has full power over all things, and that I am the servant of Allah and His Messenger."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.