Musnad Ahmad 446:0

Abu Jumu'ah Habib ibn Siba' reported: We ate lunch with the Messenger of Allah (ﷺ), and Abu Ubaydah ibn al-Jarrah was with him. Abu Ubaydah said: "O Messenger of Allah, is there anyone better than us? We accepted Islam with you and performed Jihad with you." He (ﷺ) said: "Yes, a people who will come after you, who will believe in me without having seen me."