A man enquired from the Messenger of Allah (sal Allahu alaihi wa sallam): “O Rasul Allah (sal Allahu alaihi wa sallam)! What are the rights of parents over their offspring?” The Messenger of Allah (sal Allahu alaihi wa sallam) replied: “Your entry into Paradise or Hell depends on your good or bad conduct towards your parents.” [Ibn Majah]
If you treat your parents well, the gates of Paradise will be opened for you and you will be admitted therein, provided you abstained from major sins. If you violate your parents’ rights over you, the gates of Hell will be opened for you.
Abu Hurairah (radi Allahu anhu) once saw two men. He asked one of them, “What is your relationship with that man?” The man replied, “He is my father.” Abu Hurairah (radi Allahu anhu) thereupon advised him, “Look, never call him by his name, walk ahead of him, or sit before he takes his seat.” [Al-Adab-ul Mufrad]
In other words, it is not just their material needs of food, clothing, shelter, and medicine that we need to be mindful of. We also need to show them respect and consideration by our every gesture. We should address them with titles of respect, and make sure that they are comfortable before we make ourselves comfortable.
An onlooker should be able to tell by the deference shown, who the parent is and who the child is. The respect should also be obvious of a wife for a husband, for all younger people towards people older than them regardless of their ages, and of a student for his teacher.
It is nothing but godlessness when a child talks to his parents with gritted teeth, a raised voice, or high handedness.
Abdullaah ibn Aun set two slaves free because once, when his mother called him, he raised his voice above hers. [Adh-Dhahabi, Siyar Alaam an-Nubalaa]