Answer

Wa `Alaykum as-Salamu wa Rahmatullahi wa Barakatuh.

In the Name of Allah, Most Gracious, Most Merciful.

All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear brother in Islam, thank you for your question which reflects your care to have a clear view of the teachings of Islam. Allah commands Muslims to refer to people of knowledge to get themselves well-acquainted with the teachings of Islam as well as all aspects of life.

The Prophet (peace and blessings be upon him) perfectly epitomized the Qur’anic guidance, and he won the love and admiration of his Companions so that every one of his words, acts, or even tacit approval was precisely recorded and transmitted to the following generations of the Muslim Ummah.

Aside from the acts that were done out of his human nature, Muslim jurists have regarded the acts of the Prophet (peace and blessings be upon him) as part of his Sunnah that ought to be followed and on which legislation is to be based.

Answering this question, Sheikh M. S. Al-Munajjid, a prominent Saudi Muslim lecturer and author, said:

 First, it should be noted that the basic principle concerning the actions of the Prophet (peace and blessings be upon him) is that they constitute legislation for the Ummah, and it is not permissible to say that it is only for the Prophet (peace and blessings be upon him) unless there is clear evidence to indicate that, because Almighty Allah says: “Indeed in the Messenger of Allah you have a good example to follow.” (Al-Ahzab 33:21)

Based on this principle, the Companions (may Allah be pleased with them) followed the example of the Prophet (peace and blessings be upon him) in what he did, and they did not ask him whether this action was only for him or not. One of the reports which indicate this was narrated from Abu Sa`id al-Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) was in salah and then he took off his shoes, so the people took off their shoes. When he finished he said: “Why did you take off your shoes?” They said: “O Messenger of Allah, we saw you take off your shoes, so we took off ours.” He said: “Gabriel came to me and told me that there was some impurity on them. When one of you comes to the mosque, let him turn up his shoe and look at it, and if he sees something dirty on it let him wipe it on the ground, then let him pray wearing them. ” (Ahmad)

Indeed, the Prophet (peace and blessings be upon him) got angry with some of his Companions when they thought that an action he had done was something that was exclusively for him.

It was narrated from `A’ishah, the wife of the Prophet (peace and blessings be upon him), that a man said to the Messenger of Allah (peace and blessings be upon him): “O Messenger of Allah, sometimes I wake up junub (having major ritual impurity) and I want to fast.” The Messenger of Allah (peace and blessings be upon him) said: “Sometimes I wake up junub and I want to fast, so I perform ghusl and fast.” The man said: “O Messenger of Allah, you are not like us; Allah has forgiven your previous and future sins.” The Messenger of Allah (peace and blessings be upon him) got angry, and said: “By Allah, I hope to be the one who fears Allah most among you and the most knowledgeable of what I follow.” (Abu Dawud)

Ibn Hazm commented:

“It is not permissible to say that anything the Prophet (peace and blessings be upon him) did was exclusively for him, unless there is a text to that effect. This is because he got angry with the one who said that, and everything which the Messenger of Allah (peace and blessings of Allah be upon him) got angry about is haram.”

Ibn al-Qayyim pointed out:

“The basic principle is that his Ummah share the same rulings with him except in cases where there is evidence that a ruling applies exclusively to him.”

Second, among the rulings that applied exclusively to him (peace and blessings be upon him) were: marriage without a mahr or wali; marriage to more than four women at the same time; and fasting continually for more than one day.
Ibn Hazm (may Allah have mercy on him) said:

It is not permissible for anyone after this to say concerning anything that the Prophet (blessings and peace be upon him) did that it was exclusively for him, except on the basis of a text, such as that which speaks of the woman who offered herself to him in marriage, “…a privilege for you only, not for the (rest of) the believers” (Al-Ahzab 33:50); or his fasting continually and forbidding them to do that, saying “I am not like you”; or his sleeping and praying without renewing his wudu’ and when he was asked about that, he said, “My eyes sleep but my heart does not sleep.”

Almighty Allah knows best.

Excerpted with modification and editing from www.islamqa.info