وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، قَالَ كَتَبَ أَبُو عُبَيْدَةَ بْنُ الْجَرَّاحِ إِلَى عُمَرَ بْنِ الْخَطَّابِ يَذْكُرُ لَهُ جُمُوعًا مِنَ الرُّومِ وَمَا يَتَخَوَّفُ مِنْهُمْ فَكَتَبَ إِلَيْهِ عُمَرُ بْنُ الْخَطَّابِ أَمَّا بَعْدُ فَإِنَّهُ مَهْمَا يَنْزِلْ بِعَبْدٍ مُؤْمِنٍ مِنْ مُنْزَلِ شِدَّةٍ يَجْعَلِ اللَّهُ بَعْدَهُ فَرَجًا وَإِنَّهُ لَنْ يَغْلِبَ عُسْرٌ يُسْرَيْنِ وَأَنَّ اللَّهَ تَعَالَى يَقُولُ فِي كِتَابِهِ ‏{‏يَا أَيُّهَا الَّذِينَ آمَنُوا اصْبِرُوا وَصَابِرُوا وَرَابِطُوا وَاتَّقُوا اللَّهَ لَعَلَّكُمْ تُفْلِحُونَ ‏}‏

Yahya related to me from Malik that Zayd ibn Aslam had said thatUbayda ibn al-Jarrah had written to Umar ibn al-Khattab mentioning tohim a great array of Byzantine troops and the anxiety they werecausing him. Umar ibn al-Khattab wrote in reply to him, "Whateverhardship befalls a believing slave, Allah will make an opening for himafter it, and a hardship will not overcome two eases. Allah theExalted says in His Book, 'O you who trust, be patient, and vie inpatience; be steadfast and fear Allah, perhaps you will profit.' "(Sura 3 ayat 200). Translation Not Available

Book Ref: Muwatta Imam Malik Book 21 Hadith 967
Web Ref:  Muwatta Imam Malik Book 21 Hadith 6