Jamieson, Fausset and Brown on Hebrews 12:20

20. 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 Ex 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.