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).
USC-MSA web (English) reference: Book 21, Hadith 6
Arabic reference: Book 21, Hadith 967