Parashas Tetzaveh · Passuk 28:28
Chabad.org — English translation + Rashi
Torah Temimah points to Yoma 72a.
Sefaria — Exodus 28:28
Sefaria — Yoma 72a
E-Daf — Yoma 72a
English: Rabbi Elazar teaches that one who deliberately separates the breastpiece from the ephod violates a prohibition and is liable for lashes, based on the command that the breastpiece must not be loosened from the ephod.
On the daf / in context: See the cited source for the full section.
Derash on the verse.
The connection between the breastpiece and ephod is not merely descriptive: the prohibition “it shall not be loosened” is treated by Chazal as a binding prohibition.