The Prophet ﷺ said, "Whoever does not show mercy to our young and acknowledge the right of our elders is not one of us."
عن النبي ﷺ قال: من لم يرحم صغيرنا، ويعرف حق كبيرنا فليس منا.
Abu Dawud (4943), Ahmad (7073), Bukhari in Adab al-Mufrad (354), and Hakim (1/62) all narrated it, all from the hadith of Sufyan bin Uyayna, who said, Ibn Abu Najeeh narrated to us, from Ubaydullah bin Amir, from Abdullah bin Amr, and he mentioned it. Its chain is hasan on account of Ubaydullah bin Amir, whom Ibn Main declared trustworthy, as found in the History of Darimi (469). As for Hakim, he said, "Sahih according to the criterion of Muslim, for he relied upon Abdullah bin Amir Yahsubi, though the two of them did not report it." This contains an error, for he is not Abdullah bin Amir Yahsubi, from whom Muslim narrated, but rather he is Ubaydullah bin Amir, as found in the chain of Ahmad and the Adab al-Mufrad of Bukhari. Ubaydullah bin Amir is the Makkan, who belongs among the narrators of Abu Dawud alone.