Jewish traditions across different eras and regions devote considerable attention to sexuality. Sexuality is the subject of many narratives and laws in the Tanakh (Hebrew Bible) and rabbinic literature. In Judaism, sexuality is viewed as having both positive and negative potential, depending on the context in which it is expressed. Many sources express a positive attitude towards sex between a married couple. On the other hand, sexual activity is also viewed as a grave sin if it is outside of the bounds of permissible behavior. Attitudes towards sexuality within marriage Laws and Biblical sources According to medieval Rabbinical enumerations of the 613 commandments, the commandment to procreate () is the first mitzvah in the Torah. This commandment was understood by the rabbis to be only binding on men; women are exempt. One of the common explanation for this was because childbirth puts them in physical danger, therefore they cannot be ordered to accomplish an act that put them at risk. According to many thinkers, the central nature of this mitzvah is due to the fact that God desires for the world to be populated. There is another Torah commandment known as onah which obligates a man to provide pleasurable sexual intercourse to his wife on a regular basis (if she desires it), even if they have already had children, or are incapable of having children. requires a man who has been married within the last year to "gladden" his wife at home, rather than joining the army to fight in a war which is ongoing. In later Jewish tradition, this is understood as a general requirement for every husband to stay at home with his wife for the first year of marriage, and for them to "rejoice" together. Maimonides permits a married couple to engage in nearly any form of sexual activity: In many sources, it is recommended that husband and wife have sex on Shabbat. Often, this is said to be related to the obligation to delight in the Sabbath. There are also though other reasons that contributed to this tradition, including saying that this is the only day of the week when Torah scholars have time, or that this is in order to imitate cosmic unions that happens on Friday night between God and the Shekihnah, as imagined by the Kabbalists. Any emission of semen by a man makes him ritually impure, and if this occurs during sex