The following are some of the supplications that have been transmitted.
Ash-Shaf’i states that it has been related from Salim ibn ‘Abdullah, on the authority of his father that the Prophet would say for ishsqa’: “O Allah, give us a saving rain, productive, plentiful, general, continuous. O Allah, give us rain and do not make us among the despondent. O Allah, (Your) slaves, land, animals, and (Your) creation all are suffering and seek protection. And we do not complain except to You. O Allah, let our crops grow, and let the udders be refilled. Give us from the blessings of the sky and grow for us from the blessings of the earth. O Allah, remove from us the hardship, starvation, and barrenness and remove the affliction from us as no one removes afflictions save Thee. O Allah, we seek Your forgiveness as You are the Forgiving, and send upon us plenteous rains.” Ash-Shaf’i said: “I prefer that the imam would supplicate with that (prayer). “
Sa’d reported that for ishsqa’, the Prophet would supplicate: “O Allah, let us be covered with thick clouds that have abundant and beneficial rain, frequently making a light rain upon us and sprinkling upon us with lightning. O Allah, You are full of majesty, bounty and Honour.” This is related by Abu ‘Awanah in his Sahih.
‘Amr ibn Shuaib relates from his father, on the authority of his grandfather, that for istisqa’, the Prophet would say: “O Allah, provide water for Your slaves and Your cattle, display Your mercy and give life to Your dead lands.” This is related by Abu Dawud.
It is preferred for the one who is making this supplication to raise his hands with the back of his hands toward the sky. Muslim records from Anas that the Prophet would point with the back of his hands during ishsqa’.
It is also preferred, upon seeing the rain, to say: “O Allah, make it a beneficial rain” and he should uncover part of his body to the rain. On the other hand, if one fears that there is too much rain, one should say: “O Allah give us mercy and do not give us punishment, calamaties, destruction or flooding. O Allah, make it upon the woods, farms and trees. Make it around us and not upon us.”
All of this is authentic and confirmed from the Prophet sallallahu alehi wasallam.