"Permitted to you, on the night of the fasts, is the approach to your wives. They are your garments and ye are their garments. Allah knoweth what ye used to do secretly among yourselves; but He turned to you and forgave you; so now associate with them, and seek what Allah Hath ordained for you, and eat and drink, until the white thread of dawn appear to you distinct from its black thread; then complete your fast Till the night appears; but do not associate with your wives while ye are in retreat in the mosques. Those are Limits (set by) Allah: Approach not nigh thereto. Thus doth Allah make clear His Signs to men: that they may learn self-restraint." - Quran 2:187 (read more)

"Narrated Qatada: Anas bin Malik said, "The Prophet used to visit all his wives in a round, during the day and night and they were eleven in number." I asked Anas, "Had the Prophet the strength for it?" Anas replied, "We used to say that the Prophet was given the strength of thirty (men)." And Sa'id said on the authority of Qatada that Anas had told him about nine wives only (not eleven)." - Sahih Bukhari 1:5:268 (read more)

"Discipline. The husband has the right to discipline his wife if she disobeys him in something good, not if she disobeys him in something sinful, because Allaah has enjoined disciplining women by forsaking them in bed and by hitting them, when they do not obey. The Hanafis mentioned four situations in which a husband is permitted to discipline his wife by hitting her." - Sheikh Muhammed Salih Al-Munajjid