Allah Almighty says in Surah al-Asra: the tongue must be kind " ولا تقل لهما اُف"- "Fie on you"; in other word, even try not to express an iota of disgust because Allah Almighty is not happy with that. A very important goodness toward the parents is to be a polite, dignified child with serene and placid personality. Speaking correctly, studying and making a living legitimately and in a correct and lawful way can also bring about parents' happiness and satisfaction which is another kind of goodness toward parents.
source : erfan.ir
