Sunan of Abu Dawood Book 15, Hadith 2631

حَدَّثَنَا أَبُو صَالِحٍ، مَحْبُوبُ بْنُ مُوسَى أَخْبَرَنَا أَبُو إِسْحَاقَ الْفَزَارِيُّ، عَنْ مُوسَى بْنِ عُقْبَةَ، عَنْ سَالِمٍ أَبِي النَّضْرِ، مَوْلَى عُمَرَ بْنِ عُبَيْدِ اللَّهِ - يَعْنِي ابْنَ مَعْمَرٍ وَكَانَ كَاتِبًا لَهُ - قَالَ كَتَبَ إِلَيْهِ عَبْدُ اللَّهِ بْنُ أَبِي أَوْفَى حِينَ خَرَجَ إِلَى الْحَرُورِيَّةِ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم فِي بَعْضِ أَيَّامِهِ الَّتِي لَقِيَ فِيهَا الْعَدُوَّ قَالَ ‏"‏ يَا أَيُّهَا النَّاسُ لاَ تَتَمَنَّوْا لِقَاءَ الْعَدُوِّ وَسَلُوا اللَّهَ تَعَالَى الْعَافِيَةَ فَإِذَا لَقِيتُمُوهُمْ فَاصْبِرُوا وَاعْلَمُوا أَنَّ الْجَنَّةَ تَحْتَ ظِلاَلِ السُّيُوفِ ‏"‏ ‏.‏ ثُمَّ قَالَ ‏"‏ اللَّهُمَّ مُنْزِلَ الْكِتَابِ وَمُجْرِيَ السَّحَابِ وَهَازِمَ الأَحْزَابِ اهْزِمْهُمْ وَانْصُرْنَا عَلَيْهِمْ ‏"‏ ‏.‏

Salim Abu Al Nadr, client of ‘Umar bin ‘Ubaid Allaah that is Ibn Ma'mar who Salim was his (‘Umar's) secretary reported "When ‘Abd Allah bin Abi Afwa went out to the Haruriyyah (Khawarij), he wrote to him (‘Umar bin ‘Ubaid Allaah), The Messenger of Allah(ﷺ) said on a ceratin day when he was fighting with the enemy. O people do not desire to meet the enemy, ask Allaah, Most High, for health and security. When you meet them (the enemy) have patience and endurance, you should know that paradise is under the shade of swords. He then said "O Allaah, Who sends down the Book, makes the cloud to travel and rotes the confederates, tout them and give us victory over them."