Anas bin Malik (May Allah be pleased with him) reported:
Messenger of Allah (SAW) said, "If a young man honours an older person on account of his age, Allah appoints someone to show reverence to him in his old age"



وعن أنس رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم : "ما أكرم شاب شيخًا لسنه إلى قيض الله له من يكرمه عند سنه" ((
رواه الترمذي

See translation