Matthew

Matthew 24:14 - "And this gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then shall the end come."

Mark

Mark 13:36 - "Lest coming suddenly he find you sleeping."

Luke

Luke 4:10 - "For it is written, He shall give his angels charge over thee, to keep thee:"

John

John 8:57 - "Then said the Jews unto him, Thou art not yet fifty years old, and hast thou seen Abraham?"