Sahih al-Bukhari 1005
Sahih al-Bukhari · Book 15: Invoking Allah for Rain (Istisqaa) · Going out of the Prophet (pbuh) to offer Istisqa' prayer
Narrated `Abbad bin Tamim's uncle:
حَدَّثَنَا أَبُو نُعَيْمٍ ، قَالَ حَدَّثَنَا سُفْيَانُ ، عَنْ عَبْدِ اللَّهِ بْنِ أَبِي بَكْرٍ ، عَنْ عَبَّادِ بْنِ تَمِيمٍ ، عَنْ عَمِّهِ ، قَالَ خَرَجَ النَّبِيُّ صلى الله عليه وسلم يَسْتَسْقِي وَحَوَّلَ رِدَاءَهُ.
The Prophet (p.b.u.h) went out to offer the Istisqa' prayer and turned (and put on) his cloak inside out.