The Messenger of Allah ﷺ said, "Whoever does not show mercy to our young and honor our elderly is not one of us."
أن رسول الله ﷺ قال: من لم يرحم صغيرنا ويجل كبيرنا فليس منا.
Bukhari narrated it in Adab al-Mufrad (356), Ibn Abu Dunya in Nafaqah ala al-Iyal (187), and Tabarani in Kabir (8/236), all of them through Yazid bin Harun, who said, Walid bin Jameel informed us, from Qasim bin Abdul-Rahman, from Abu Umama, and he related it.Its chain is hasan on account of Walid bin Jameel and Qasim bin Abdul-Rahman, for the two of them make the hadith hasan so long as their error has not been established.