حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، أَخْبَرَنَا هَمَّامٌ، عَنْ قَتَادَةَ، عَنْ أَبِي الْمَلِيحِ، عَنْ أَبِيهِ، أَنَّ يَوْمَ، حُنَيْنٍ كَانَ يَوْمَ مَطَرٍ فَأَمَرَ النَّبِيُّ صلى الله عليه وسلم مُنَادِيَهُ أَنِ الصَّلاَةُ فِي الرِّحَالِ ‏.‏

Narrated Usamah ibn Umayr al-Huzali: The rain was falling on the day when the Battle of Hunayn took place. The Prophet (PBUH), therefore, commanded that the people should offer their prayer in their camps. Translation Not Available

Book Ref: Sunan Abi Dawud Book 2 Hadith 1057
Web Ref:  Sunan Abi Dawud Book 3 Hadith 1052