Parashas Shemos · Passuk 3:15
Chabad.org — English translation + Rashi
Torah Temimah points to Yerushalmi Yoma 3:7 (verified).
Sefaria — Exodus 3:15
Sefaria — Yerushalmi Yoma 3:7
English: “This is My name forever” — when the High Priest would pronounce the Name on Yom Kippur, the hearers would not move from the place until it became concealed from them, as it is written “this is My name le’olam” — written le’alem.
On the daf / in context: See the cited source for the full section.
Custom
Chazal link the Yom Kippur utterance of the Name to the spelling that implies concealment after the moment of revelation.