Certain rabbis, such as Maimonides, believed that concubines are strictly reserved for kings, and thus that a commoner may not have a concubine; indeed, such thinkers argued that commoners may not engage in any type of sexual relations outside of a marriage. Maimonides was not the first Jewish thinker to criticize concubinage; for example, it is severely condemned in Leviticus Rabbah. Other rabbis, such as Nachmanides, Samuel ben Uri Shraga Phoebus, and Jacob Emden, strongly object to the idea that concubines should be forbidden.