(118) بَابُ الْخُرُوجِ إِلَى الْمَبْقَلَةِ، وَحَمَلِ الشَّيْءِ عَلَى عَاتِقِهِ إِلَى أَهْلِهِ بِالزَّبِيلِ
Ibn 'Abbas said, " 'Umar said, 'Let us go forth to the land ofour people.' Ubayy ibn Ka'b and I were at the back of the people. A cloudgathered. Ubayy said, 'O Allah, remove its harm from us!' We met the peopleand their mounts were wet. They said, 'What fell on us did not fall onyou!' I said, 'He asked Allah Almighty to remove its harm from us.' 'Umarsaid, 'Why didn't you include us in your supplication?'"
Reference: Al-Adab Al-Mufrad 235
In-book reference: Book 11, Hadith 15
English translation: Book 11, Hadith 235