The mitzva of ona is for the husband to couple with his wife, in an atmosphere of love and ecstasy, and to pleasure her as best he can, until her ecstasy climaxes in orgasm; he remains coupled with her until he ejaculates inside her vagina (see also below, 2:1). This is the meaning of the verse “He shall not withhold her food, her clothing, or her conjugal rights” (Shemot 21:10). Since the husband’s physical capacity is limited, the frequency of the mitzva is determined by what his physical capacity and professional responsibilities make possible. Those who are in good health and who live comfortably without having to exert themselves too much must fulfill the mitzva of ona daily. Ordinary laborers are obligated twice a week. Men whose work requires them to leave home are required to fulfill this mitzva once a week. In addition, if either spouse desires intimacy, the other spouse must be responsive (below, 2:7-8).
This mitzva is the essence and foundation of marriage. A man who does not perform this mitzva in order to cause his wife pain is in violation of the Torah prohibition, “He shall not withhold…her conjugal rights.” If he does not perform it out of simple negligence, but does not intend to hurt his wife, he violates a rabbinic prohibition. Some say that even in such a case, he violates a Torah prohibition.
Moreover, through the mitzva of ona, husband and wife fulfill the mitzva to “love your fellow as yourself” in its most perfect form: each of them looks out for the other’s well-being as best they can. And since the greatest pleasure that people can experience in this world is connected to the mitzva of ona, a man who deprives his wife of this joy and pleasure oppresses her, since no one but him can bring her this joy. Likewise, a woman who deprives her husband of this joy and pleasure oppresses him, for no one else can fill this void for him (2:1 below).
Dereliction of this mitzva is the principal grounds for divorce. If a husband declares that his wife repulses him and that he has no interest in sexual relations with her and bringing her pleasure as often as duty requires, she is entitled to file for divorce and to receive the compensation specified in her ketuba (marriage contract). Even if the husband is willing to couple with her but adds, “I cannot unless we are both clothed,” he must divorce her and pay the ketuba, since he is unwilling to couple with her lovingly, with no barrier between them. Similarly, if a wife does not consent to sexual relations with her husband at the frequency specified, or is only willing if she remains clothed, he has the right to divorce her without paying her ketuba (Ketubot 48a; SA EH 76:13). Spouses who refuse to keep to the specified frequencies are called “rebellious,” for they are rebelling against the sacred duty they accepted on themselves when they married (Ketubot 63a; SA EH 77; see below ch. 2, sections 7-8, 11-12, and n. 6).
Others say that we can derive from an additional verse, “He will give happiness to the woman he has married” (Devarim 24:5), that a husband must bring his wife pleasure through the mitzva of ona. Although this verse refers only to his exemption from military service during their first year of marriage, we nevertheless can infer that whenever they are together, he has a mitzva to bring his wife joy and pleasure through the mitzva of ona (Smak §285; Ohel Mo’ed, Sha’ar Isur Ve-heter, derekh 11, netiv 2; and Sefer Ḥaredim 20:8). Commenting on Pesaḥim 72b, Rabbeinu Ḥananel agrees that there is a positive commandment of ona, but he derives it from yet another verse: “Return to your tents” (Devarim 5:27; see section 6 below).
A corollary of this mitzva is that a husband should sleep in the same room with his wife even when she is a nidda (Eruvin 63b). We will explain below (2:2) why this mitzva is formulated as the husband’s obligation. In any case, it is a mitzva and a duty for the wife to respond to her husband with joy for the fulfillment of this mitzva.