レビ記 19:32

מפני שיבה תקום THOU SHALT RISE UP BEFORE A HOARY HEAD — One might think this reverence is also due to an ignorant old man! Scripture however says זקן — "thou shalt honour the face of the ״זקן — and זקן denotes only one who has acquired wisdom (Sifra, Kedoshim, Chapter 7 12;Kiddushin 32b). AND THOU SHALT HONOR THE FACE OF THE OLD — What does the term "honoring” an old man imply? That one should not sit in his seat nor contradict his statements. One might think that one is allowed to close one’s eyes as though one does not see him (the old man)! Scripture however states "but be afraid of thy God”, because in this thing it is given to the heart of him only who does the action to know the motive that prompts him for no one has an insight into this except himself, and in reference to any thing where it is given only to the heart to know, Scripture states “and thou shalt be afraid of thy God Who knows thy secret thoughts״ (Sifra, Kedoshim, Chapter 7 14; Kiddushin 32b).

מִפְּנֵ֤י שֵׂיבָה֙ תָּק֔וּם וְהָדַרְתָּ֖ פְּנֵ֣י זָקֵ֑ן וְיָרֵ֥אתָ מֵּאֱלֹהֶ֖יךָ אֲנִ֥י יְהֹוָֽה׃ {ס}        

Thou shalt rise up before the hoary head, and honour the face of the old man, and fear thy God: I am the Lord.