Man and woman agree together to lead married life and this agreement is called nikah (marriage), and the two parties accept the responsibilities and obligations and thus live together as husband and wife. For nikah it is necessary that both man and woman have attained the age of puberty-the age of full bloom and strength (4:6, 40:67). Nikah is not possible without mutual consent of both the parties in the presence of at least two witnesses, one from the side of the man and the other from the side of woman. (Man and woman have free choice to marry each other (4:3, 19) Men have been forbidden to marry women against their will, they cannot marry without obtaining consent of women and thus become their masters instead of companion. (4:19) The criterion for selection of spouse should be the unanimity of ideology and faith in Islam, and this is the reason why a momin (Believer-man) is forbidden to marry a mushrika (Unbeliever-woman) vice versa, and thus to save home from becoming hell whereas Allah wants it to become heaven (2:221).
Nikah should be performed in a declared manner, and the relationship between the spouses should not be kept a secret. If it is performed secretly it is not legal. (4:25; 5:5) The Quran has not suggested any ceremony for nikah, nor it has mentioned about involvement of a (third) person to perform it. Since nikah is an agreement between two parties, government can formulate rules and regulations (marriage Act), and it has to be performed accordingly.
For those who are capable of getting married the society has to provide facilities for nikah. (24:32) Those who could not get facilities to get married should keep themselves chaste by self-control till they get alliance. [(24:33)-VI, p.803] Prostitution is prohibited.
Married couple is forbidden from sexual Intercourse when:
(I) The women is not in normal physical condition i.e. during menses, and after this period they can have it as per the natural laws (2:222);
(ii) When either of them or both are observing fast (of course from dawn to dusk) (2:187); and
(iii) Even from dusk to dawn when one is in retreat in the mosque (for some assignment). (2:187)
Forbidden Women for Nikah
Certain women (relationships) are forbidden for nikah. They are:
(1) Yours mothers
(2) Your daughters
(3) Your sisters
(4) Your father’s sisters
(5) Your mother’s sisters
(6) Your brother’s daughters
(7) Your sister’s daughters
(8) Your foster mothers
(9) Your foster sisters
(10) Mothers of your wives
(11) Your stepdaughters, which have been brought up under your guardianship and are born of wives with whom you have had marital relations. If you have not had marital relations then the prohibition does not apply.
(12) Wives of your real sons.
(13) It is also prohibited to have in marriage two sisters at the same time.
Also forbidden to you in marriage are those women who are already married except those whom you already possess. (4:23,24)
A Muslim man should not marry a mushrika (Unbeliever woman) until she accepts Islam; likewise Muslim woman should not marry mushrik man until he accepts Islam. (2:221) A Muslim woman cannot marry a man from amongst the people who believe in the earlier scriptures (5:5)
Adapted from: "Family Life in Islam" by: "Dr. Mir Mustafa Hussain"