Musannaf Ibn Abi Shayba 36:68

Abu Bakr narrated to us, he said: Muhammad ibn Abi Ubaydah narrated to us, he said: My father narrated to me, from al-A’mash, from al-Qasim ibn Abd al-Rahman, from his father, he said: Abdullah said: I have seen myself as the sixth of six, there being no Muslim on the face of the earth other than us.