Sahih Bukhari Volume 008, Book 076, Hadith Number 423.

Narated By Sahl bin Sa'd As-Sa'idi : We were in the company of Allah's Apostle in (the battle of) Al-Khandaq, and he was digging the trench while we were carrying the earth away. He looked at us and said, "O Allah! There is no life worth living except the life of the Hereafter, so (please) forgive the Ansar and the Emigrants."