Leviticus 19:32 - Matthew Poole's English Annotations on the Holy Bible

Thou shalt rise up, to do them reverence when they pass by, for which end they were obliged, as the Jews say, presently to sit down again when they were past, that it might be manifest they arose out of respect to them. Fear thy God; a reason of the former precept, both because old men in some respects do most resemble God, who is styled the Ancient of days, Daniel 7:9,13, and because this respect is due to such, if not for themselves, who may be unworthy or contemptible, yet for God's sake, who requires this reverence, and whose singular blessing old age is.