Jamieson, Fausset & Brown, on Heb 12:19

“And the sound of a trumpet, and the voice of words, which they that heard excused themselves, that the word might not be spoken to them:”

“trumpet--to rouse attention, and herald God's approach (Exo 19:16). entreated that the word should not be spoken--literally, "that speech should not be added to them"; not that they refused to hear the word of God, but they wished that God should not Himself speak, but employ Moses as His mediating spokesman. "The voice of words" was the Decalogue, spoken by God Himself, a voice issuing forth, without any form being seen: after which "He added no more" (Deu 5:22).”

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