John Gill Commentary Matthew 5:2

"and he opened his mouth and taught them, saying," — Matthew 5:2 (ASV)

And he opened his mouth
He spoke with a clear and strong voice, that all the people might hear him; and with great freedom, utterance, and cheerfulness, and things of the greatest moment and importance;

and taught them ;
not his disciples only, but the whole multitude, who heard him with astonishment; see (Matthew 7:28Matthew 7:29) . Some things in the following discourse are directed to the disciples in particular, and others regard the multitude in general.