“O Allah, shower upon us abundant rain, beneficial not harmful, swiftly and not delayed.”
اللّهُمَّ اَسْقِـنا غَيْـثاً مُغيـثاً مَريئاً مُريـعاً، نافِعـاً غَيْـرَ ضَّارٌ، عاجِـلاً غَـيْرَ آجِلٍ
Allaahumma ‘asqinaa ghaythan mugheethan maree’an maree’an, naafi’an ghayradhaarrin, ‘aajilan ghayra ‘aajilin.
Abu Dawud 1/303. See also Al-Albani Sahih Abu Dawud 1/216.