Jami` at-Tirmidhi 556
جامع الترمذي#556SahihAbbad bin Tamim narrated from his uncle:"The Messenger of Allah went out with the people to seek rain. So he led them in prayer for two Rak'ah, reciting aloud in them, turning his upper wrap around, raising his hands, requesting rain, and facing the Qiblah
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 6:13