Musnad Ahmad 74:0

Narrated to us by Yahya ibn Sa’id, from Ibn ‘Ajlan, who said: Narrated to me ‘Amr ibn Shu’ayb, from his father, from his grandfather, that the Messenger of Allah (ﷺ) said: "The one who is not merciful to our young ones, and does not acknowledge the honor of our elders, is not one of us."