Acts 7:30

And when forty years were expired, there appeared to him in the wilderness of mount Sina an angel of the Lord in a flame of fire in a bush.

And when forty years were expired - (see the note at Acts 7:23).

There appeared to him in the wilderness of mount Sina - the wilderness or desert of that mountain-range which went, it would appear, under the general name of Horeb, but is here called (from the individual mountain whence the law was given) Sinai:

An Angel of the Lord. The better attested reading is simply 'an' or 'the angel.' Whichever way we render it, 'the Angel of the covenant' is clearly meant, since He immediately calls Himself Yahweh (H3068) (compare Acts 7:38). In a flame of fire in (or 'of') a bush, [ batou (G942)]. This bush-burning, yet not consumed-was no doubt designed to hold forth the two chief characters by which the Church of God has been in every age distinguished-persecuted, but not forsaken; cast down, but not destroyed; chastened, but not killed; dying, but behold it lives (2 Corinthians 4:9; 2 Corinthians 6:9).