Sahih Bukhari Volume 1, Book 9, Hadith 596

حَدَّثَنَا مُعَاذُ بْنُ فَضَالَةَ، قَالَ حَدَّثَنَا هِشَامٌ، عَنْ يَحْيَى، عَنْ أَبِي سَلَمَةَ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، جَاءَ يَوْمَ الْخَنْدَقِ بَعْدَ مَا غَرَبَتِ الشَّمْسُ، فَجَعَلَ يَسُبُّ كُفَّارَ قُرَيْشٍ قَالَ يَا رَسُولَ اللَّهِ مَا كِدْتُ أُصَلِّي الْعَصْرَ حَتَّى كَادَتِ الشَّمْسُ تَغْرُبُ‏.‏ قَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ وَاللَّهِ مَا صَلَّيْتُهَا ‏"‏‏.‏ فَقُمْنَا إِلَى بُطْحَانَ، فَتَوَضَّأَ لِلصَّلاَةِ، وَتَوَضَّأْنَا لَهَا فَصَلَّى الْعَصْرَ بَعْدَ مَا غَرَبَتِ الشَّمْسُ، ثُمَّ صَلَّى بَعْدَهَا الْمَغْرِبَ

Narrated By Jabir bin 'Abdullah : On the day of Al-Khandaq (the battle of trench.) 'Umar bin Al-Khattab came cursing the disbelievers of Quraish after the sun had set and said, "O Allah's Apostle I could not offer the 'Asr prayer till the sun had set." The Prophet said, "By Allah! I, too, have not prayed." So we turned towards Buthan, and the Prophet performed ablution and we too performed ablution and offered the 'Asr prayer after the sun had set, and then he offered the Maghrib prayer.