Is a son considered undutiful if he undertakes a permissible act without informing his parents, fearing their anger?

The pleasure of Allah, the Exalted, is linked to the pleasure of one's parents, and His displeasure to their displeasure. Obedience to them is obligatory and takes precedence over performing what is permissible (mubah) and abandoning what is recommended (mustahabb). Obedience to them is obligatory if their prohibition of a permissible act is for a valid reason; otherwise, it is not. If their prohibition is based merely on foolishness, it should be disregarded. A son's performance of a permissible act is not considered disobedience, especially if it is without their knowledge, unless it results in harm to them or deprives them of a benefit by its omission.