"Honor your father and your mother that you may long endure on the land that the LORD your God is assigning to you." Love and respect of parents is the source of all mercy, compassion and goodness, as is the respect of a nation’s elders, judges and teachers, without which it is impossible to sustain order in a state for very long.
For one who does not love his parents and abandons them in their times of distress, and has no pity on them, is but a cruel individual with a heart of stone. What mercy has such a person for the poor, for orphans or for widows? If a person has no respect for his parents and does not obey their bidding, how can he be expected to respect his elders, or a judge’s verdict?
Note that the Ten Commandments are written in singular form. God speaks to the People of Israel as to a single individual. God commands you – the entire nation, to sustain and protect the love and honor of parents, for they are the source of mercy and compassion. Respect elders, Cohanim and judges, so that they may endure, for the benefit of the society of Israel and for order in the state, so that their land be protected for a long time.