It is narrated from Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) that he said: "We were with the Prophet (peace and blessings be upon him) at the Trench; we were digging and he (peace and blessings be upon him) was carrying the earth, and he (peace and blessings be upon him) said: 'O Allah, there is no true life except the life of the Hereafter, so forgive the Ansar and the Muhajirun.'"
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5928