4. midst of . . . city . . . midst of Jerusalem--This twofold designation marks more emphatically the scene of the divine judgments.
      a mark--literally, the Hebrew letter Tau, the last in the alphabet, used as a mark ("my sign," Job 31:35, Margin); literally, Tau; originally written in the form of a cross, which TERTULLIAN explains as referring to the badge and only means of salvation, the cross of Christ. But nowhere in Scripture are the words which are now employed as names of letters used to denote the letters themselves or their figures [VITRINGA]. The noun here is cognate to the verb, "mark a mark." So in Re 7:3 no particular mark is specified. We seal what we wish to guard securely. When all things else on earth are confounded, God will secure His people from the common ruin. God gives the first charge as to their safety before He orders the punishment of the rest (Ps 31:20; Isa 26:20, 21). So in the case of Lot and Sodom (Ge 19:22); also the Egyptian first-born were not slain till Israel had time to sprinkle the blood-mark, ensuring their safety (compare Re 7:3; Am 9:9). So the early Christians had Pella provided as a refuge for them, before the destruction of Jerusalem.
      upon the foreheads--the most conspicuous part of the person, to imply how their safety would be manifested to all (compare Jer 15:11; 39:11-18). It was customary thus to mark worshippers (Re 13:16; 14:1, 9) and servants. So the Church of England marks the forehead with the sign of the cross in baptizing. At the exodus the mark was on the houses, for then it was families; here, it is on the foreheads, for it is individuals whose safety is guaranteed.
      sigh and . . . cry--similarly sounding verbs in Hebrew, as in English Version, expressing the prolonged sound of their grief. "Sigh" implies their inward grief ("groanings which cannot be uttered," Ro 8:26); "cry," the outward expression of it. So Lot (2Pe 2:7, 8). Tenderness should characterize the man of God, not harsh sternness in opposing the ungodly (Ps 119:53, 136; Jer 13:17; 2Co 12:21); at the same time zeal for the honor of God (Ps 69:9, 10; 1Jo 5:19).

JFB.