In this paper we examine the origins of a quite rare oath formula in Arabic, as expressed by a protagonist in the medieval story collection The 101 Nights. As part of the oath formula, the Deity is depicted as having spread the earth over frozen water. A perusal of ancient Muslim traditions concerning the earth’s creation sheds some light on the matter, but the substantive and linguistic picture which these traditions draw is somewhat ambiguous. We shall present some ancient Jewish traditions, some of them pre-dating the emergence of Islam, in which a dilemma on this theme is seen to arise, and would seem to have served as a background against which a somewhat unstable ancillary Muslim cosmogonical approach to the earth’s creation emerged.