spoken by angels - the Mosaic law spoken by the ministration of angels (Deu 33:2; Psa 68:17; Act 7:53; Gal 3:19). When it is said, Exo 20:1, “God spake,” it is meant He spake by angels as His mouthpiece, or at least angels repeating in unison with His voice the words of the Decalogue; whereas the Gospel was first spoken by the Lord alone.
was steadfast - Greek, “was made steadfast,” or “confirmed”: was enforced by penalties on those violating it.
transgression - by doing evil; literally, overstepping its bounds: a positive violation of it.
disobedience - by neglecting to do good: a negative violation of it.