Misyar  marriage can be defined as a marriage contract between a man and a woman, in which the woman waives some of the rights she would have in a normal Islamic marriage. This sometimes takes place when, for example, there are many women who, as they get older, find it increasingly difficult to marry. In this case a woman opts for a husband who is not able to fulfil the normal marital duties like financial maintenance, or spending adequate time with her, for example. She considers that marrying such a husband is better than remaining unmarried.

It’s noteworthy that once a marriage contract meets its Shari`ah requirements, it will be acceptable from the Islamic point of view irrespective of what people call such contract. Conditions of valid marriage are: The consent of both spouses, the consent of the wali (guardian), the payment of the dower, the presence of the witnesses, and the announcement of the contract.
It goes without saying that valid marriage should not be limited to a certain period of time; otherwise it will be reckoned as a mut`ah (temporal) marriage which is prohibited in Islam.
Dealing with this subject, the eminent Muslim scholar, Sheikh Yusuf Al-Qaradawi, states:

Misyar marriage should be viewed as a form of legal relationship between man and woman regardless of any description attached to it. This is pursuant to the juristic rule: “What matters most in contracts are motives and meaning, not the wording or structure.”
therefore, in determining the legal nature of this marriage, we should not judge things according to names, for as we know, people feel free in naming or describing something.
Stipulating certain details in the marriage contract on both sides is acceptable. For example, some scholars maintain that a woman has a right to determine the timing of marriage; i.e., it can take place at day or night, however, she can also waive this right.

therefore, based on what has been mentioned, we can state that misyar marriage, or something in similar form, has been in practice from time immemorial. It also serves the purpose of some women, who, for instance, may be rich but happen to be unable to marry at the proper time. So, such women can opt for this kind of marriage.
But I do have to make it clear that the aforementioned statement does not make me a protagonist of misyar marriage. In all my fatwas and sermons, it is not mentioned anywhere that I give any support for such marriage.
the point is that when I was asked by a journalist to state my opinion regarding this marriage, I found it a pressing religious duty to give a clear-cut opinion on something that does not make unlawful what Almighty Allah has made lawful for His servants.

therefore, if anyone seeks my opinion on this marriage, I must reply him saying: What do you mean by misyar marriage. Then, if I get an explanation that shows that in misyar marriage, all the Islamic legal requirements are met, then the marriage is valid.

those requirements are: an offer and acceptance from both parties; a specified dowry, according to the Qur’anic verse: [And give unto the women, (whom ye marry) free gift of their marriage portions] (An-Nisaa’ 4: 4), and that the contract wins the consent of the guardian. Thereby, no one has the right to brandish it as unlawful.
there is no doubt that such marriage may be somehow socially unacceptable, but there is a big difference between what is Islamically valid and what is socially acceptable. As we know, people can be cynical about the idea of an employee marrying his employer. But who can deny the validity of such a marriage if it meets all the legal requirements?
this issue, therefore, needs a cautious approach. One should not feel free to condemn an act as absolutely forbidden, merely on social repugnance. Rather, one needs to have convincing evidence to determine the legal nature of each particular act.