Charles Ellicott Commentary Matthew 10:27

"What I tell you in the darkness, speak ye in the light; and what ye hear in the ear, proclaim upon the house-tops." — Matthew 10:27 (ASV)

What I tell you in darkness — These words point to our Lord’s method of teaching, which was often esoteric, disclosed only to the chosen few and only as they were able to bear it (John 16:12). Parables, dark sayings, whispered hints, and many-sided proverbs were among the forms by which He led them to the truth.

In their work as teachers, they were not to shrink out of fear of man from making public what they had thus learned. To “proclaim on the housetops” is a natural figure for the fullest boldness and freedom in their preaching, as the flat roofs of houses were often used by criers and heralds for their announcements.