Sahih Muslim Book - 6, Hadith - 1573

وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِى شَيْبَةَ وَأَبُو كُرَيْبٍ وَزُهَيْرُ بْنُ حَرْبٍ وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ قَالَ إِسْحَاقُ أَخْبَرَنَا وَقَالَ الآخَرُونَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ إِدْرِيسَ عَنِ ابْنِ جُرَيْجٍ عَنِ ابْنِ أَبِى عَمَّارٍ عَنْ عَبْدِ اللَّهِ بْنِ بَابَيْهِ عَنْ يَعْلَى بْنِ أُمَيَّةَ قَالَ قُلْتُ لِعُمَرَ بْنِ الْخَطَّابِ ( لَيْسَ عَلَيْكُمْ جُنَاحٌ أَنْ تَقْصُرُوا مِنَ الصَّلاَةِ إِنْ خِفْتُمْ أَنْ يَفْتِنَكُمُ الَّذِينَ كَفَرُوا) فَقَدْ أَمِنَ النَّاسُ فَقَالَ عَجِبْتُ مِمَّا عَجِبْتَ مِنْهُ فَسَأَلْتُ رَسُولَ اللَّهِ -صلى الله عليه وسلم- عَنْ ذَلِكَ. فَقَالَ « صَدَقَةٌ تَصَدَّقَ اللَّهُ بِهَا عَلَيْكُمْ فَاقْبَلُوا صَدَقَتَهُ ».

It was narrated that Ya'la bin Umayyah said: "I said to 'Umar bin Al-Khattab: '...There is no sin on you if you shorten As-Salat (the prayer) if you fear that the disbelievers may put you in trial (attack you)..." But now the people are safe.' He said: 'I wondered the same thing as you are wondering, and I asked the Messenger of Allah (s.a.w) about that. He said: It is a charity that Allah has bestowed upon you, so accept His charity.'"