He went out with the Messenger of Allah ﷺ to perform the prayer for rain. The Messenger of Allah ﷺ turned his cloak inside out, turned his back toward the people, and made supplication. Then he prayed two rakats, reciting the Quran aloud.
أخبرني عمرو بن عثمان قال حدثنا الوليد عن ابن أبي ذئب عن الزهري
أنه خرج مع رسول الله ﷺ يستسقي فحول رداءه وحول للناس ظهره ودعا ثم صلى ركعتين فقرأ فجهر
Bukhari narrated it in the book of Istisqa, in the chapter on reciting aloud during Istisqa, hadith no. 1024, from the hadith of Ibn Abu Dhib. Muslim narrated it in the book of the prayer of Istisqa, hadith no. 4/894, from the hadith of Zuhri through the same chain. It is also found in Al-Kubra, hadith no. 1812.