RIDWAN (رضوان).  Arabic name meaning "one who satisfies," from rada' ("to content"). (An English and Arabic Dictionary, Catafago, 1873).  Also see Rizwan.

... Harut and Marut are, according to Alkur'an, two angels, who were believed to practice sorcery at Babylon.  It is recounted that when the angels in heaven expressed surprise at the wickedness of the sons of Adam after the prophets had been sent to them, God let them choose two of themselves to be sent down to earth. They chose Harut and Marut, who exercised their office with integrity until the planet Joharah or Venus descended in the shape of a woman, and enticed them to love her, so that when she flew away from them to heaven, they pursued her there; but Ridwan, the guardian of Paradise, did not admit them. On the intercession of some of the pious, they were permitted to choose whether their punishment for this misdemeanour should be in this world or the next. It is said that they chose the former, and are now confined at Babylon till the day of judgment; and that if any one desires to acquire the art of magic, he may go to them and learn of them, hearing their voice, but not seeing them. (Makamat, Preston, 1850)