See the notes at Matthew 8:16-17.
And at even, when the sun did set - See the notes at Matthew 8:16.
All the city - A great part of the city. A great multitude from the city.
And suffered not the devils to speak, because they knew him - They knew that he was the Messiah.
If they had spoken, they would have made that known to the people. Jesus was not desirous at that time that that should be publicly known, or that his name should be blazoned abroad. The time had not come when he wished it to be promulgated that he was the Messiah, and he therefore imposed silence on the evil spirits.