Good treatment of parents when they reach old age and be patient with them, where the Quran explicitly states this (17:23). Of course, in your question you don't say that the person was your parent. For that, I have another story to relate, which is from Muhammad's Sira (i.e. biography). Soon after he was asked to go public with the message of Allah, he called upon all the leader and elders of the tribes in Makkah for a meal where he would announce the message. It was only Ali ibn Abu Talib, a mere boy at the time, who rose up to say that he believed in his message. I think the story goes where the Prophet acknowledged Ali's courage to defy his elders and also his father who was present the time, in the very beliefs of his forefathers so openly. The elders present couldn't take this humiliation. After the incident, Abu Talib (father of Ali) would be mocked by the unbelievers, being told that in the Prophet's new preachings, his son was now more superior to him. Then only this is a story I have read, I don't have a reference to it at this present time. And as such, there may be gaps in it. And if this story is true, I think this goes to show the message of equality in Islam, where an an elderly does not become superior to somone younger, simply due to their age.