Specifically the account given in the book "Ibn Fadlan and the Land of Darkness"
Perry, John R. “Ibn Fadlan’s Journey to Russia: A Tenth‐Century Traveler from Baghdad to the Volga River by Richard N. Frye: Review by John R. Perry”. Journal of Near Eastern Studies, Vol. 68, No. 2. Chicago: The University of Chicago Press, 2009. 159-160. JSTOR.