When I washed my steps with butter, and the rock poured me out rivers of oil;
Butter - rather, cream-literally, thick milk. Wherever I turned my steps the richest milk and oil flowed in to me abundantly. Image from pastoral life. Literal washing of the feet in milk is not meant, as the second clause shows; margin, with me - i:e., near my path, wherever I walked (Deuteronomy 32:13-14). Olives amidst rocks yield the best oil. Oil in the East is used for food, light, anointing, and medicine.