part one of many

I was given permission to speak in my fathers shul (synagogue)hopefully in a few weeks. this lead me to do lots of research on one topic. I therefore will for the next few posts stick to the same topic.
Many people believe that the reason we were commanded to respect our parents is because of Hakaras Hatov (recognizing the good). Meaning, because they fed me, raised me, and did good to me I have to do good back to them.
When were we first commanded on Kibbud Av V'am (Honoring your father and mother)? I originally thought it was from the Ten Commandments. However, this is not the case. The answer is at Marah( the story of the bitter river) in parshat Bshalach. Rashi learns out of the words chok umishpat to tell us that we got shabbos, Kibbud Av and Parah Aduma (the red heifer).
In psalms 34:21 Hashem says Lchu Banim shimu li, go my children listen to me. It should say Bau (come), not Lchu (go).
Hashem is telling us to be like a child that listens to his father even when the father is not around because he does it out of love. Not like a slave that only does what he has to out of fear when his master is around. Therefore Hashem is saying as children I expect you to listen even when you go.
In the desert (in Marah) we did not rely on our parents. We got food and shelter from Hashem. This is one of the reasons we got the mitzvah of Kibbud Av V'am in the desert to teach us that we do it because we are commanded, not because we owe our parents gratitude.