Musannaf Ibn Abi Shayba 33:325

Abu Mu'awiyah narrated to us, from al-A'mash, from 'Umarah, from 'Abd al-Rahman ibn Yazid, from 'Abdullah, who said: "You are more frequent in fasting, more frequent in prayer, and more frequent in striving than the companions of the Messenger of Allah, peace and blessings of Allah be upon him, yet they were better than you." They said: "Why, O Abu 'Abd al-Rahman?" He said: "They were more ascetic regarding the world and more desirous of the Hereafter."