The ruling on Ila' is prohibited because of the oppression and harm done to women.
Its pillars are six: One who makes an oath, something with which a person swears, something to fulfill or prohibit by an oath, a duration, a form, and a wife.
(1) The condition of the one who makes an oath should be a husband who has full capacity, has the free will to make choices, and is able to have sexual intercourse with his wife. So, other than a husband cannot make Ila' such as a master. People who do not have full capacity such as intoxicated cannot make Ila'. The one who is forced to Ila' cannot make Ila', likewise the one who cannot have sexual intercourse with his wife such as a complete eunuch or a paralyzed.
(2) The condition of the sworn by is: It must be one of three: One of Allah's name, one of His Attributes, or suspending Ila' on divorce or emancipation, or making a commitment such as vowing to offer Salah, fasting and other kinds of righteous actions. Whoever swears by something other than Allah shall not be an oath breaker and no penance due to him if he breaks his oath such as to say: By the Ka`bah, by dawn, by night, or something of the like; in this case he is not practicing Ila' because all these are outside the range of oath.
(3) The condition of the thing which should be fulfilled or abandoned is to abandon the sexual intercourse with one's wife, so there is no Ila' if a husband prohibits enjoying any part of her body or abandoning sexual intercourse with her during menstruation or during the state of Ihram.
(4) The condition of the duration is: To be more than four months, so if the period is less than four months, it will not be a type of Ila' but just an oath because a woman can endure the separation of her husband for four months. `Amr ibn Dinar said: `Umar ibn Al Khattab went out one night then he heard a woman saying:
The night is long and dark, and I have no one to play with.
By Allah, unless I fear Him, this bed would have shaken all over.
Thereupon, `Umar asked his daughter Hafsah (may Allah be pleased with her): How long a woman can endure the separation of her husband? She said: Six months or four months. Then `Umar said: I shall not prevent soldiers in the army to be away from home for more than that period.
(5) The form of Ila’ should be a word that indicates Ila' either explicitly such as: I shall not have sexual intercourse with you or I shall not have a shower due to Janabah (major ritual impurity related to sexual discharge); and this type does not require intention. So, if someone claims that he does not mean sexual intercourse, he shall not be believed by the judge.
The other form is implicit: It is every word that may imply the meaning of sexual intercourse besides other meanings and this type requires an intention such as: I shall not catch you, come to you, lie on you, do not touch you, I shall tease you, I shall harm you, I shall not enter on you, I shall not gather my head and yours, I shall not lie with you, I shall not approach you, I shall not spend the night with you, my skin shall not touch your skin, and I shall not approach your bed. This type of Ila' requires an intention and shall be effective before the judge.
(6) A husband may practice Ila' in regard to his wife and his revocable divorced wife.