Sahih Bukhari Volume 005, Book 058, Hadith Number 140.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 58. Merits of the Helpers in Madina (Ansaar)
Narated 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 honor the Ansar and the Emigrants."