Sahih Bukhari Volume 4, Book 56, Hadith 3001

حَدَّثَنَا سَعِيدُ بْنُ أَبِي مَرْيَمَ، أَخْبَرَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، قَالَ أَخْبَرَنِي زَيْدٌ ـ هُوَ ابْنُ أَسْلَمَ ـ عَنْ أَبِيهِ، قَالَ كُنْتُ مَعَ عَبْدِ اللَّهِ بْنِ عُمَرَ ـ رضى الله عنهما ـ بِطَرِيقِ مَكَّةَ، فَبَلَغَهُ عَنْ صَفِيَّةَ بِنْتِ أَبِي عُبَيْدٍ شِدَّةُ وَجَعٍ، فَأَسْرَعَ السَّيْرَ حَتَّى إِذَا كَانَ بَعْدَ غُرُوبِ الشَّفَقِ، ثُمَّ نَزَلَ فَصَلَّى الْمَغْرِبَ وَالْعَتَمَةَ، يَجْمَعُ بَيْنَهُمَا، وَقَالَ إِنِّي رَأَيْتُ النَّبِيَّ صلى الله عليه وسلم إِذَا جَدَّ بِهِ السَّيْرُ أَخَّرَ الْمَغْرِبَ وَجَمَعَ بَيْنَهُمَا‏

Narrated By Aslam : While I was in the company of 'Abdullah bin 'Umar on the way to Mecca, he received the news of the severe illness of Safiya bint Abi Ubaid (i.e. his wife), so he proceeded at greater speed, and when the twilight disappeared, he dismounted and offered the Maghrib and 'Isha prayers together and said, " I saw the Prophet delaying the Maghrib prayer to offer it along with the 'Isha when he was in a hurry on a journey."