Sahih al-Bukhari 2834
Narrated Anas:
Allah's Messenger (ﷺ) went towards the Khandaq (i.e. Trench) and saw the Emigrants and the Ansar digging 
in a very cold morning as they did not have slaves to do that for them. When he noticed their fatigue 
and hunger he said, "O Allah! The real life is that of the Here-after, (so please) forgive the Ansar and 
the Emigrants." In its reply the Emigrants and the Ansar said, "We are those who have given a pledge 
of allegiance to Muhammad that we will carry on Jihad as long as we live."
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ، حَدَّثَنَا مُعَاوِيَةُ بْنُ عَمْرٍو، حَدَّثَنَا أَبُو إِسْحَاقَ، عَنْ حُمَيْدٍ، قَالَ سَمِعْتُ أَنَسًا ـ رضى الله عنه ـ يَقُولُ خَرَجَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِلَى الْخَنْدَقِ فَإِذَا الْمُهَاجِرُونَ وَالأَنْصَارُ يَحْفِرُونَ فِي غَدَاةٍ بَارِدَةٍ، فَلَمْ يَكُنْ لَهُمْ عَبِيدٌ يَعْمَلُونَ ذَلِكَ لَهُمْ، فَلَمَّا رَأَى مَا بِهِمْ مِنَ النَّصَبِ وَالْجُوعِ قَالَ اللَّهُمَّ إِنَّ الْعَيْشَ عَيْشُ الآخِرَهْ فَاغْفِرْ لِلأَنْصَارِ وَالْمُهَاجِرَهْ‏.‏ فَقَالُوا مُجِيبِينَ لَهُ نَحْنُ الَّذِينَ بَايَعُوا مُحَمَّدًا عَلَى الْجِهَادِ مَا بَقِينَا أَبَدًا