Parashas Yisro · Passuk 20:23
Chabad.org — English translation + Rashi
Torah Temimah points to Mechilta (verified).
Sefaria — Exodus 20:23
Sefaria — Mechilta
English: One who prays must place his feet evenly, like the kohanim, of whom it is written “you shall not go up by steps upon My altar,” and they would walk heel beside big toe.
In context: See the cited source for the full section.
Derash on the verse.
The measured, modest gait of the kohanim on the ramp is transferred to the posture of every person standing in the Amidah.