Exodus 20:26

He seems to mean the steps of ladders, or others of the same nature, which could suddenly be made, and were proper for their present condition, where there was danger of the following inconvenience. For afterwards God appointed an altar ten cubits high, 2 Chronicles 4:1; though some conceive they went not up to that by steps, but by an insensible ascent upon the ground raised by degrees for that purpose. But if the priests did go up to it by steps, God provided against the indecency here mentioned, by prescribing linen breeches to them in that service. That thy nakedness be not discovered thereon; for these linen breeches were not yet appointed, and the manner then and there was for men to wear long coats or gowns like women. God would remove all appearance or occasion of immodesty, especially in sacred persons and things; and the rather, to show his detestation of that impudence and filthiness which was very usual in some of the solemnities and worships of the heathen.