Obligations are according to Ability.

On the authority of Abu Hurairah ‘Abd-ur-Rahmaan ibn Sakhr (ra) who said: I heard the Messenger of Allah (saws) say:

“What I have forbidden for you, avoid. What I have ordered you (to do), do as much of it as you can. For verily, it was only the excessive questioning and their disagreeing with their Prophets that destroyed (the nations) who were before you”. [Related by al-Bukhaaree and Muslim]

Explanation of Hadeeth
The wording of this hadeeth in Saheeh Muslim, from Abu Hurairah (ra), states: The Messenger of Allah (saws) addressed us and said:

“O People! Hajj has been made obligatory upon you, so perform the Hajj.” So a man asked: “Is that every year, O Messenger of Allah?” So the Prophet (saws) remained silent until the man repeated his question three times. Then he said: “If I had said ‘yes’ then it would have become obligatory upon you (i.e. every year), and you would not have been able to do so. Do not ask me about that which I have left (unspecified), for verily the nations before you were destroyed by their excessive questioning and their disagreeing with their Prophets. So if I order you with something then do as much of it as you are able, and if I forbid you from something then keep away from it.”

And the Scholars of Usool (i.e. in Fiqh) have differed over the issue of the Command to perform an action – does it imply repetition? That is, if we are ordered to do something then does that automatically imply that we must do it repeatedly? Or does it mean that doing it once is sufficient unless otherwise specified? For example, we are commanded with Hajj but that is just once in a lifetime, but we are also commanded with Salaah and that is every day. So most of the Fuqahaa (jurists) have decided that a command does not automatically imply repetition. Others have said that we do not rule that it implies repetition nor do we rule that it does not imply repetition, except with a further evidence that indicates one or the other. And this hadeeth is a proof for those who have the latter opinion. For if there were an automatically implied ruling of either repetition or no repetition then the Prophet (saws) would not have replied “If I had said yes then it would have become obligatory, and you would not have been able to do that.” Rather, if there had been an automatic implication of repetition or otherwise, then the man would not have asked the question in the first place.

 

And as for his (saws) statement “Do not ask me about that which I have left (unspecified)” then this apparently indicates that a command does not imply repetition, and also that the origin of all affairs is that they are not waajib, until the Sharee’ah specifies them as being waajib. And this is the correct position according to the majority of the Scholars of Usool.

And his (saws) statement: “If I had said yes it would have become obligatory upon you” is an evidence that he (saws)) would make ijtihaad in rulings, and that it was not binding upon him that all rulings be made by Revelation.

And his (saws) statement: “What I have ordered you, do as much of it as you can” is an important Principle of Islaam, and is from his Concise speech. And based upon this principle are countless other rulings – such as the Prayer of one who is unable to complete some of its pillars or conditions, then he performs what he is able to from that which remains. And the one who cannot wash all the necessary limbs of wudoo’, washes that which he is able to. And in the case of removing evil, then if one is not able to remove it entirely then one removes what one is able to. And many other affairs like these, as are well known from the Books of Fiqh. And this hadeeth is similar to the statement of Allah:

“And have taqwaa of Allah, as much as you are able” [at-Taghaabun, 16]

And as for His statement

“O you who believe! Fear Allah as He should be feared” [aal 'Imraan, 102]

then it has been said that this is abrogated by the aayah “And have taqwaa of Allah, as much as you are able”. However, what is correct is that it is not abrogated, but rather the first aayah is an explanation of this aayah, and makes clear what is intended by it. And it has been said that “fearing Allah as He should be feared” means obeying Him all in that He has commanded, and staying away from all that He has forbidden, and Allah does not order us except with that which we are able to do, as verily Allah has said:

“Allah does not burden a soul more than it can bear” [al-Baqarah, 286]

“and (Allah) has not laid upon you in religion any hardship” [al-Hajj, 78]

And as for his (saws) statement: “and what I have forbidden you from then avoid it” then this is to be taken to apply generally in all situations, except if one has a necessity, such as eating meat from an animal which has not been correctly slaughtered if one’s life is in danger or what is similar to that, then that is not considered to be forbidden. However, in all conditions other than that of necessity the individual is not considered to have fulfilled this forbiddance of the Prophet (saws) until he leaves all those things which the Sharee’ah forbids. So he does not fulfill the forbiddance if he continues to practice even one of the forbidden things. This is in opposition to what has been commanded to do, for in terms of the commands we must do whatever we are able.

And in his (saws) statement: “verily the nations before you were destroyed due to their excessive questioning and disagreeing with their Prophets”, then this was mentioned after his saying “Do not ask me about that which I have left (unspecified)”. And this implies that we should not be excessive in questioning, as then we would be similar to the Banu Israa’eel when it was said to them: “Sacrifice a cow”. So if they had taken these words upon their apparent meaning and sacrificed any cow they would have fulfilled the command. But because they insisted on asking many questions regarding its color, its appearance, its work etc, the matter became difficult for them, until they were able to find a suitable cow only after a great search and paying a large sum of money. So they were blameworthy for this, and our Prophet Muhammad (saws) feared the same for his Ummah.

Summary
* That what is Haraam must be avoided.
* That one must make sure that one has a satisfactory plea to present to Allaah for not doing what the Messenger (saws) has ordered.
* That one must not ask too many questions. Ideally, one only wants to know what Islaam says [about a thing] and do that.
* That asking too many questions and disagreeing with the Messenger (saws) can cause our destruction. If it happened to the people before us it can happen to us too.