The Messenger of Allah ﷺ said, "Look at those who are below you and do not look at those who are above you, for that is more fitting so that you do not belittle the favor of Allah." Abu Muawiya added, "upon you."
حدثنا أبو معاوية ووكيع حدثنا الأعمش عن أبي صالح
قال رسول الله ﷺ انظروا إلى من هو أسفل منكم ولا تنظروا إلى من هو فوقكم فإنه أجدر أن لا تزدروا نعمة الله قال أبو معاوية عليكم
Its isnad is sahih. Muslim (2:385) and Ibn Majah (4142) also related it, both by way of Abu Muawiya and Waki, with this same isnad. As for the wording at the end, "Abu Muawiya said, 'upon you'," this means that Abu Muawiya added this phrase in his narration, saying, "for that is more fitting so that you do not disdain Allah's favor upon you." This addition from Abu Muawiya is also established in the versions of Muslim and Ibn Majah. See also 7317 and 8132.As for the phrase "so that you do not disdain," Ibn Athir said, "izdira means contempt, belittlement, and finding fault. It is on the pattern of ifti'al, from 'zarayta alayhi zirayatan' [I disdained him], meaning when one finds fault with him."