Sahih Muslim | Book 42 | Hadith Number 7068

Narrated by Abu Huraira
Abu Huraira reported that Allah's Messenger (may peace be upon him) said: When one of you looks at one who stands at a higher level than you in regard to wealth and physical structure he should also see one who stands at a lower level than you in regard to these things (in which he stands) at a hi-her level (as compared to him).