The Prayer for Seeking Rain
According the founder of the Hanafi school, and the massly transmitted narrations (dhahir al-riwaya), there is no sunna prayer to be performed in congregation for the purpose of seeking rain (istisqa’).
Rather, it is a supplication and seeking of forgiveness. The basis of which are the words of Allah Most High, “Seek pardon of your Lord. Lo! He was ever Forgiving. He will let loose the sky for you in plenteous rain.” [Qur’an, 71:10-11]