وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ وَزُهَيْرُ بْنُ حَرْبٍ وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ قَالَ إِسْحَاقُ أَخْبَرَنَا وَقَالَ الآخَرُونَ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ إِدْرِيسَ، عَنِ ابْنِ جُرَيْجٍ، عَنِ ابْنِ أَبِي عَمَّارٍ، عَنْ عَبْدِ اللَّهِ بْنِ بَابَيْهِ، عَنْ يَعْلَى بْنِ أُمَيَّةَ، قَالَ قُلْتُ لِعُمَرَ بْنِ الْخَطَّابِ ‏ end actual hadith container 2‏ 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 ‏"‏ ‏.‏

Yahya b. Umayya said: I told 'Umar b. al-Khattab that Allah had said:" You may shorten the prayer only if you fear that those who are unbelievers may afflict you" (Qur'an, iv. 101), whereas the people are now safe. He replied: I wondered about it in the same way as you wonder about it, so I asked the Messenger of Allah (PBUH) about it and he said: It is an act of charity which Allah has done to you, so accept His charity. Translation Not Available

Book Ref: Sahih Muslim Book 6 Hadith 1461
Web Ref:  Sahih Muslim Book 4 Hadith 686 a