Matthew 10:27

What I tell you in darkness— That is, in private. In the light, means in public. In the next words our Lord alludes to a custom among the Jews, whose teachers were accustomed to have their interpreters, who received the dictates of their masters whispered in the ear, and then publicly proposed them to all. The last words, that preach ye upon the house-tops, refers to another custom of making things public, by proclaiming them on the flat roofs of the houses in the East. The Mollahs among the Turks at this day proclaim on the top of their mosques, that "God is great, and Mahomet is his prophet," as a signal for the people to come to public prayers. See on ch. Matthew 24:17 and Wynne's new translation.