The sign of the Son of Man in heaven (to shmeion tou uiou tou anqrwpou en ouranwi). Many theories have been suggested like the cross in the sky, etc. Bruce sees a reference to Daniel 7:13 "one like the Son of man" and holds that Christ himself is the sign in question (the genitive of apposition). This is certainly possible. It is confirmed by the rest of the verse: "They shall see the Son of man coming." See Matthew 16:27 ; Matthew 26:64 . The Jews had repeatedly asked for such a sign (Broadus) as in Matthew 12:38 ; Matthew 16:1 ; John 2:18 .