And Naaman said, Shall there not then, I pray thee, be given to thy servant two mules' burden of earth? for thy servant will henceforth offer neither burnt offering nor sacrifice unto other gods, but unto the LORD. 2 Kings 5:17
Two mules’ burden of earth. i.e. of the Holy Land, for constructing an altar to the God of Israel in Syria. Naaman held the heathen view that a deity was only powerful in the country which recognized him; and therefore that outside Palestine, God could only be worshipped on soil from Israel’s land!
(Hertz, Dr. J.H., The Pentateuch and Haftorahs, 2nd Ed., Soncino Press, London, 1992, pg 468)