People came crying to the Prophet (ﷺ) because there was no rain. Jabir bin Abdillah (RA) tells us what happened. The Prophet (ﷺ) said -
اَللَّهُمَّ اسْقِنَا غَيْثًا مُغِيْثًا مَرِيْئًا مَرِيْعًا نَافِعًا غَيْرَ ضَارٍّ عَاجِلًا غَيْرَ آجِلٍ
Transliteration
Allaahumma 'asqinaa ghaythan mugheethan maree-an maree'an, naafi'an ghayra dhaarrin, 'aajilan ghayra 'aajil
Translation
O Allah, shower upon us abundant rain, beneficial not harmful, swiftly and not delayed.
Allāhumma 'asqinā ghaythan mughīthan marī'an murī`a, nāfi`an ghayra ḍārr, `ājilan ghayra ājil. Ask Allah for lots of rain, the helpful kind that comes soon.
Muslims gather together for salat istisqa. They say special duas. They ask Allah: send rain that is good for everyone - for crops, people, and animals.
Say Allāhumma-sqinā ghaythan mughīthan, marīʿan nāfiʿan, ghayra dharrin, ʿajilan ghayra ājil. You are asking Allah: give us rain that helps, not rain that hurts.
Pray two rak'ahs with extra takbirs. The imam gives a short talk. Then everyone makes dua asking Allah for His kindness. This follows the sunnah.
Go to an open space or mosque after the sun rises. The imam leads two rak'ahs with extra takbirs. He gives a short talk. Everyone asks Allah for rain together.