Jamieson, Fausset & Brown, on Heb 12:20

“For they did not endure that which was said: And if so much as a beast shall touch the mount, it shall be stoned.”

“that which was commanded--"the interdict" [TITTMANN]. A stern interdictory mandate is meant. And--rather, "Even if a beast (much more a man) touch," &c. or thrust through with a dart--omitted in the oldest manuscripts. The full interdict in Exo 19:12-13 is abbreviated here; the beast alone, being put for "whether man or beast"; the stoning, which applies to the human offender, alone being specified, the beast's punishment, namely, the being thrust through with a dart, being left to be understood.”

Imported from an open dataset — not yet checked against the printed edition.