Musnad Ahmad 31:56

Sufyan narrated to us, from ‘Amr, who heard Jabir narrating from Abu Sa’id al-Khudri, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "A time will come upon the people when a group of people will go out to fight, and it will be said: 'Is there among you anyone who was a companion of the Messenger of Allah (peace and blessings of Allah be upon him)?' It will be said: 'Yes,' and they will be granted victory. Then a group of people will go out to fight, and it will be said: 'Is there among you anyone who was a companion of a companion of the Messenger of Allah (peace and blessings of Allah be upon him)?' They will say: 'Yes,' and they will be granted victory. Then a group of people will go out to fight, and they will say: 'Is there among you anyone who was a companion of a companion of the companions of the Messenger of Allah (peace and blessings of Allah be upon him)?' They will say: 'Yes,' and they will be granted victory."