We were with Allah's Messenger (ﷺ) in the Trench, and some were digging the trench while we were carrying the earth on our shoulders. Allah's Messenger (ﷺ) said, 'O Allah! There is no life except the life of the Hereafter, so please forgive the Emigrants and the Ansar."
Sahih al-Bukhari Book 64, Hadith 142
← Previous Hadith That the Prophet (ﷺ) inspected him on the day of Uhud while he was fourteen years old, and the Prophet (ﷺ) did not allow him to take part in the battle. He was inspected again by the Prophet (ﷺ) on the day of Al- Khandaq (i.e. battle of the Trench) while he was fifteen years old, and the Prophet (ﷺ) allowed him to take Part in the battle.

Sahih al-Bukhari Book 64, Hadith 141 Next Hadith → Allah's Messenger (ﷺ) went out towards the Khandaq (i.e. Trench) and saw the Emigrants and the Ansar digging the trench in the cold morning. They had no slaves to do that (work) for them. When the Prophet saw their hardship and hunger, he said, 'O Allah! The real life is the life of the Hereafter, so please forgive Ansar and the Emigrants." They said in reply to him, "We are those who have given the Pledge of allegiances to Muhammad for to observe Jihad as long as we live."

Sahih al-Bukhari Book 64, Hadith 143