Rukh bav ('grandmother Rukh') is the benevolent household spirit of the Tabasarans, most often seen as an old woman. When she lies upon a sleeping person that person becomes fortunate and rich, whence the proverb 'Happy is he on whom Rukh bav has lain'; when she settles on the family's food-stores they never fail. She is petitioned in domestic formulas urging her toward the oil-jug, the money-chest and the flour-barrel, and in the tale-tradition she carries a cap of invisibility and a magic ball of thread. She may also appear in zoomorphic, anthropomorphic or formless shape. Ethnographers classify her only loosely as a house-spirit, since her dwelling and her patron role are weakly defined; unlike the clearly hostile birth-demon Al, she is generally kindly, though narratives also know a darker, oppressive Rukh.