Single Action, Multiple Rewards

Hazrat Imam Ja'far as-Sadiq (a.s.) said, 
"What prevents you from serving your parents in their life and death? The Holy Prophet (s.a.w.s.) remarks about the goodness to parents after death. "Perform their 'namaz' (if some wajib prayers have been omitted by them, the eldest son should perform them himself, or have them fulfilled by someone else on payment. However, if no wajib prayer is remaining upon them, then he could pray Nawafil Namaz for them or have them performed on payment.) Pay Sadaqah on their behalf. Complete their Qaza fasts and fulfill the obligation of their Hajj. Whatever you do, both of you will be rewarded (i.e.you and your parents).

Apart from this, goodness to parents carries double rewards. One for the action itself, and second for the benevolence towards the parents.

Praying (Dua) For the Parents and Seeking Forgiveness On Their Belief

It is narrated from the Holy Prophet (s.a.w.s.) that a man approached him and asked whether his parents have any rights upon him after their death? The Holy Prophet (s.a.w.s.) replied, 
"Yes, pray Namaz for them, seek forgiveness on their behalf, respect their tradition, and be good to their relatives." 
(Al Kafi)

When is Obedience to the Parents Wajib?

The orders and restraints of the parents are of no significance with respect to the wajib acts and the Divine prohibitions. For example if the parents order the child to drink wine or restrain him from the obligatory prayers and fasts, they should not be obeyed. It is expressly mentioned in this Verse of Surah Luqman: 
"And if they contend with you that you should associate with Me what you have no knowledge of, do not obey them..." 
(Surah Luqman 31:15)

The traditions also support this Ayat: 
"No Obedience of a creature in contravention to the Divine command." 
(Behaarul Anwaar)

Apart from these circumstances, obedience to parents is obligatory with regards to the Makruh and Mubah acts. The same applies to the Wajib-e-Kifai.

If by performing these actions, the parents are displeased or hurt, it is 'Haraam', a Greater Sin and causes one to be 'Aaq-e-Waledain'. Suppose the son wishes to proceed on a non-obligatory journey and the parents restrain him as they fear some harm for him, or because they cannot bear to be separated from him; and the son disobeys them and goes ahead with the journey, such a journey is Haraam. It is a journey of sin. Salaat and Fasting is not Qasr for this journey. In short, anything that causes displeasure and hurts the parents, is absolutely Haraam.

Obedience to parents is not obligatory in the following cases:
When it causes unbearable hardships or harm. For instance, if they restrain the son from marriage when he feels the need for it. Or they order the son to divorce his wife without a sound reason. If such an action will result in harm to both the spouses, it is not obligatory to obey the parents.

As far as I know, it is not obligatory to obey parents even in cases where they do not get angry or hurt if their commands are disobeyed.

As far as possible one should obey their orders and restrain from opposing them. Especially when the parents advise their children for their own benefit and without any selfish motive.

Disagreement among the Parents

If a situation arises when there is a disagreement between the parents on any subject, as far as possible, one should try to pacify and satisfy both of them. However, if it is not possible then the wish of the mother should be given precedence.

We have already seen the reasons why her rights far exceed those of the father. She is also more deserving of obedience because being a woman she is more sensitive in comparison to men. The mother is easily disturbed by the slightest hurt caused by her child. She becomes restless and uncontrollable due to her motherly feelings. In contrast, the father exercises reason and intelligence and being less emotional, is much less affected. He would realise that the son is obeying the mother because of the very special status granted to her by Allah and not because he intends to disobey his father due to disregard for him.

Permission of the Parents is Necessary

The Islamic Shariat has prescribed certain matters wherein it is necessary to obtain the permission of both the parents. Or at least of one of them. For example, the Wajib-e-Kifai acts like Jehad, or the Mustahab acts like the recommended fasts, or matters like taking an oath, vow and promises. In all such cases it is Wajib to obtain the parents' permission. The First Martyr1 had mentioned ten topics on the rights of parents in his book "Qawaid". It will be appropriate to mention them.

Journey of the Child and the Martyr's viewpoint

1) Mubah and Mustahab journey without the permission of parents is Haraam. However a business journey and the journey undertaken for acquiring knowledge is allowed according to some Mujtahids.

2) Some Jurists are of the opinion that, obedience to parents is Wajib upon the child in every condition where there exists a doubt. Hence if the parents order their son or daughter to eat with them, and if there is doubt regarding the food, it is incumbent to obey the parents. Because, obedience to parents is Wajib while avoiding food in case of doubt, is Mustahab.

3) If it is time for prayers and the parents would like to get some work done, it is necessary to carry out the orders before offering Namaz. Here again the offering of Namaz at the earliest is Mustahab whereas the obedience to parents is Wajib.

Refraining From Namaz-e-Jamat

1) Parents cannot prevent their child from performing Namaz in congregation unless it causes some problem to them. For example, the absence of the son, while he goes for Fajr or Isha prayers, may cause them anxiety regarding their own securityor the safety of their property. Or, it may make them apprehensive about the son's safety.

2) If it is not absolutely obligatory (Wajib-e-Aini) the parents can stop their son from going on Jehad.

3) Regarding the commands, which are Wajib-e-Kifai, the parents can prevent their son or daughter only if there is a certainty or a chance of the Wajib being fulfilled by other people.

4) Some jurists are of the opinion that if one is praying a recommended prayer, he can interrupt it if his parents call him.

5) One must forgo recommended fasts if the father disallows them.

6) In the matter regarding vows and promises, if the parents are against it, then one must not disobey them.

7) It is the duty of the son to ensure that he causes no harm to his parents. And if someone else intends to harm them, the son must do everything in his capacity to ward off the harm.