one-third.
There is no fixed rotation of nights between concubines (surriyyāt) and free wives. The husband may stay with a concubine for as long as he wishes, provided that this does not harm his wife, and it is disliked for him to pass the night elsewhere out of anger with her. He is not sinful if he abstains from intercourse with the concubine.
When a man undertakes a journey, he may take his wife with him so long as she is safe with him and he treats her well; if she refuses to travel, her maintenance is no longer due. If he has several wives, he may not take one of them along except by casting lots; on his return he resumes the normal rotation among them. Some have said he may choose any of them without drawing lots, but the first view is sounder. He must not have intercourse with one wife on the day allotted to another without her permission. Mālik disliked a man’s purchasing from his wife—or a wife from her co-wife—the right to a day.
A man may practise ʿazl (withdrawal) with his wife if she is a slave, provided her master permits it; her own permission is immaterial. He may not practise ʿazl with a free woman except with her consent, though he may do so with his own slave-women without theirs. Withdrawal does not bar the attribution of a child to him unless he claims that an istibrāʾ waiting period had been observed. Questions of paternity are treated in the Book of Liʿān, the Book of Acknowledgements, and the Book of Claims.
He must not approach a woman from the rear for intercourse, whether she is menstruating or not. The wife is the guardian of her husband’s household and property: she must safeguard herself and his wealth, not leave the house without his permission, and neither squander nor give away any of his property—even a trifle—unless he freely agrees. She is, however, allowed to give charity from his wealth in small amounts that he is known to approve.
She should not oppose him, in his absence or presence, in any matter she knows would displease him. It is her right that he spend on her according to his means and feed her from what he himself eats, without maintaining a constant frown toward her. He should not shun her bed unless he intends by it to discipline her for her own reform, and he ought to remind her to fear Allah.