Sahih Bukhari Volume 5, Book 63, Hadith 3798

حَدَّثَنَا آدَمُ، حَدَّثَنَا شُعْبَةُ، عَنْ حُمَيْدٍ الطَّوِيلِ، سَمِعْتُ أَنَسَ بْنَ مَالِكٍ ـ رضى الله عنه ـ قَالَ كَانَتِ الأَنْصَارُ يَوْمَ الْخَنْدَقِ تَقُولُ نَحْنُ الَّذِينَ بَايَعُوا مُحَمَّدَا عَلَى الْجِهَادِ مَا حَيِينَا أَبَدَا فَأَجَابَهُمُ اللَّهُمَّ لاَ عَيْشَ إِلاَّ عَيْشُ الآخِرَهْ فَأَكْرِمِ الأَنْصَارَ وَالْمُهَاجِرَهْ

Narrated By Anas bin Malik : On the day of the battle of the Trench (i.e. Ghazwat-ul-Khandaq) the Ansar used to say, "We are those who have given the pledge of allegiance to Muhammad for Jihad (i.e. holy fighting) as long as we live." The Prophet , replied to them, "O Allah! There is no life except the life of the Hereafter; so please honour the Ansar and the Emigrants."