What I tell you in darkness, that speak ye in light: and what ye hear in the ear, that preach ye upon the housetops. What I tell you in darkness - A man ought to preach that only which he has learned from God's Spirit, and his testimonies; but let him not pretend to bring forth any thing new, or mysterious. There is nothing that concerns our salvation that is newer than the new covenant; and in that there are, properly speaking, no mysteries: what was secret before is now made manifest in the Gospel of the ever-blessed God. See Ephesians 3:1-12.
What ye hear in the ear - The doctor who explained the law in Hebrew had an interpreter always by him, in whose ears he softly whispered what he said; this interpreter spoke aloud what had been thus whispered to him. Lightfoot has clearly proved this in his Horae Talmudicae, and to this custom our Lord here evidently alludes. The spirit of our Lord's direction appears to be this: whatever I speak to you is for the benefit of mankind, - keep nothing from them, declare explicitly the whole counsel of God; preach ye, (κηρυξατε proclaim), on the house-tops. The houses in Judea were flat-roofed, with a ballustrade round about, which were used for the purpose of taking the air, prayer, meditation, and it seems, from this place, for announcing things in the most public manner. As there are no bells among the Turks, a crier proclaims all times of public worship from the house-tops. Whoever will give himself the trouble to consult the following scriptures will find a variety of uses to which these housetops were assigned. Deuteronomy 22:8; Joshua 2:6; Judges 9:51; Nehemiah 8:16; 2 Samuel 11:2; 2 Kings 23:12; Isaiah 15:3; Jeremiah 32:29, and Acts 10:9.
Lightfoot thinks that this may be an allusion to that custom, when the minister of the synagogue, on the Sabbath eve, sounded with a trumpet six times, upon the roof of a very high house, that from thence all might have notice of the coming in of the Sabbath. The first blast signified that they should heave off their work in the field: the second that they should cease from theirs in the city: the third that they should light the Sabbath candle, etc.