Someone remarked to the Imam, “By Allah! No one is superior to you as regards lineage and ancestry.” He replied, “All the virtues my ancestors possessed were due to their piety and obedience of Allah and not due to something else.” The man said, “By Allah! You are better than ordinary people.” The Imam replied with perfect humility, “O man, do not swear by Allah regarding this. One who has better piety than me is superior to me. By Allah! This verse has not been abrogated:
Surely the most honorable of you with Allah is the one among you most careful (of his duty). (Surah Hujurat 49:13)
He pointed out towards a Negro slave and said, “From the aspect of my relationship with the Prophet alone, I do not consider myself better than this slave. However, if I perform a good deed I would be better than him on the basis of that deed.”
On the basis of his humility and respect, Imam Ridha’ (a.s) used to meet the poorest of the poor without any sort of formality. Mamun did not like this, and one day he objected to it. The Imam said, “I can forsake the heir-apparency but I cannot give up my poor brethren.”
Reference :Akhlaq al-A’imma, Morals & Manners of the Holy Imams