Musannaf Ibn Abi Shayba 27:779

Zayd ibn al-Hubab narrated to us, he said: Abdullah ibn al-Ala Abu al-Zubayr al-Dimashqi narrated to us, he said: Abdullah ibn Amir narrated to us, from Wathilah ibn al-Asqa, he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "You will continue to be in goodness as long as there is among you one who saw me and accompanied me. By Allah, you will continue to be in goodness as long as there is among you one who saw the one who saw me and accompanied the one who accompanied me."