Hisnul Muslim 169

For rain

اللّهُمَّ اسْقِنَا غَيْثاً مُغِيثاً مَرِيئاً مَرِيعاً، نَافِعاً غَيْرَ ضَارٍّ، عَاجِلاً غَيْرَ آجِلٍ

Allaahumma 'asqinaa ghaythan mugheethan maree'an maree'an, naafi'an ghayradhaarrin, 'aajilan ghayra 'aajilin.

O Allah, shower upon us abundant rain, beneficial not harmful, swiftly and not delayed.