The freed slave of ʿUmar bin 'Ubaidullah who was ʿUmar's clerk: ʿAbdullah bin Abi ʿAufa wrote him (i.e. ʿUmar) a letter that contained the following:-- "Once Messenger of Allah ﷺ (during a holy battle), waited till the sun had declined and then he got up among the people and said, "O people! Do not wish to face the enemy (in a battle) and ask Allah to save you (from calamities) but if you should face the enemy, then be patient and let it be known to you that Paradise is under the shades of swords." He then said,, "O Allah! The Revealer of the (Holy) Book, the Mover of the clouds, and Defeater of Al-Ahzab (i.e. the clans of infidels), defeat them infidels and bestow victory upon us."  

أَنَّ رَسُولَ اللَّهِ ﷺ فِي بَعْضِ أَيَّامِهِ الَّتِي لَقِيَ فِيهَا انْتَظَرَ حَتَّى مَالَتِ الشَّمْسُ ثُمَّ قَامَ فِي النَّاسِ قَالَ أَيُّهَا النَّاسُ لاَ تَتَمَنَّوْا لِقَاءَ الْعَدُوِّ وَسَلُوا اللَّهَ 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.”  

أَنَّ رَسُولَ اللَّهِ ﷺ 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  

[Machine] "That the Haruriyya should invade, so I said to his scribe, and I had a friend who copied it for me, so he did. Indeed, the Messenger of Allah ﷺ used to say, 'Do not wish to meet the enemy, but ask Allah for well-being. But if you meet them, then be patient and know that Paradise is under the shade of swords.' He then looked, when the sun set, directing his face towards his enemy, then he said, 'O Allah, the Revealer of the Book, the Mover of the clouds, the Defeater of the factions, defeat them and grant us victory over them.'"  

أَنْ يَغْزُوَ الْحَرُورِيَّةَ فَقُلْتُ لِكَاتِبِهِ وَكَانَ لِي صَدِيقًا انْسَخْهُ لِي فَفَعَلَ إِنَّ رَسُولَ اللهِ ﷺ كَانَ يَقُولُ لَا تَمَنَّوْا لِقَاءَ الْعَدُوِّ وَسَلُوا اللهَ ﷻ الْعَافِيَةَ فَإِذَا لَقِيتُمُوهُمْ فَاصْبِرُوا وَاعْلَمُوا أَنَّ الْجَنَّةَ تَحْتَ ظِلَالِ السُّيُوفِ قَالَ فَيَنْظُرُ إِذَا زَالَتِ الشَّمْسُ نَهَدَ إِلَى عَدُوِّهِ ثُمَّ قَالَ اللهُمَّ مُنْزِلَ الْكِتَابِ وَمُجْرِيَ السَّحَابِ وَهَازِمَ الْأَحْزَابِ اهْزِمْهُمْ وَانْصُرْنَا عَلَيْهِمْ