John Gills Exposition of the Bible Commentary - Deuteronomy 18:20
But the prophet which shall presume to speak in my name ,.... Pretending a mission and commission from God, and yet was never sent by him, like the prophets in Jeremiah 23:21 , which I have not commanded him to speak ; which though true was not to be spoken in a public manner, by assuming a public office, without a divine authority or a commission from God, and much less what was false, and never commanded to be spoken at all by any: or, that shall speak in the name of other gods ;... read more
Matthew Henry's Complete Commentary - Deuteronomy 18:15-22
Here is, I. The promise of the great prophet, with a command to receive him, and hearken to him. Now, 1. Some think it is the promise of a succession of prophets, that should for many ages be kept up in Israel. Besides the priests and Levites, their ordinary ministers, whose office it was to teach Jacob God's law, they should have prophets, extraordinary ministers, to reprove them for their faults, remind them of their duty, and foretel things to come, judgments for warning and deliverances... read more