Is obeying everything the parents (the father and mother) says? I have a friend who obeys and listens to everything his parents says, is it obligatory to obey and listen every single word they say, and the words they say out of concern. Is it a sin if we choose to deny and not listen to the parents word?

Qur’an teaches us to be kind and obedient to our parents. At the same time, the Qur’an warns us not to obey them when it comes to sins. Meaning, you cannot obey them for example if they ask you to do things contrary to the teachings of Allah.
It’s important we maintain our respect for them even if we disagree with them.