Exodus 20:23

ולא תעלה במעלות AND THOU SHALT NOT GO UP BY STEPS [TO MY ALTAR] — When thou buildest an ascent to the altar thou shalt not construct it of steps, échelons in old French, but it shall be even (i. e. the surface shall be unbroken) and sloping (cf. Rashi on Exodus 27:5). אשר לא תגלה ערותך THAT THY NAKEDNESS BE NOT UNCOVERED — because on account of these steps you will have to take large paces and so spread the legs. Now, although this would not be an actual uncovering of one’s nakedness (of the parts usually kept covered), since it is written, (Exodus 28:42) “And thou shalt make for them (the priests) linen breeches [to cover the flesh of their nakedness]”, still the taking of large paces is near enough to uncovering one’s nakedness that it may be described as such, and you would then be treating them (the stones of the altar) in a manner that implies disrespect. Now the following statement follows logically à fortiori: How is it in the case of stones which have no sense (feeling) to be particular about any disrespect shown to them? Scripture ordains that since they serve some useful purpose you should not treat them in a manner that implies disrespect! Then in the case of your fellow-man who is made in the image of your Creator and who is particular about any disrespect shown to him, how much more certain is it that you should not treat him disrespectfully! (Mekhilta)

וְלֹֽא־תַעֲלֶ֥ה בְמַעֲלֹ֖ת עַֽל־מִזְבְּחִ֑י אֲשֶׁ֛ר לֹֽא־תִגָּלֶ֥ה עֶרְוָתְךָ֖ עָלָֽיו׃ {פ}

Neither shalt thou go up by steps to my altar, that thy nakedness be not exposed on it.