The Olivet discourse and its parallels.
Paul to the Thessalonians, the Didache, and the apocalypse of John.
All three synoptic gospels portray Jesus, during the last week of his life, speaking to (at least some of) his disciples about things to come. Matthew and Mark explicitly show him sitting on the mount of Olives. Luke merely places him near the temple, but after the discourse states that Jesus was teaching in the temple by day and spending each night on mount Olivet, another name for the same mountain.
This stretch of teaching has come to be called the Olivet discourse.
For Matthew the Olivet discourse is the last of five discourses, each of which ends with the phrase και εγενετο οτε ετελεσεν ο Ιησους, and it happened when Jesus finished (Matthew 26.1a). For Mark the Olivet discourse is the teaching that brings a mighty apocalyptic undercurrent to the surface of this secretive gospel at last. For Luke the Olivet discourse is the climax of the many teachings that Jesus has been giving in the temple ever since entering Jerusalem on a donkey (compare Luke 20.1 with 21.37-38).
Olivet consists of both triple and double tradition material (though Luke locates all, or nearly all, the double tradition material in an apocalyptic controversy with the Pharisees, Luke 17.20-37, in his central section), as well as special Matthean, Marcan, and Lucan material. The Matthean version is by far the longest. The diversity of presentation is such that one might suspect the entire scene a synoptic construction (it does not appear in any form in John), except that the Olivet outline reappears in several different early Christian works (the first epistle to the Thessalonians, the apocalypse of John, and the Didache), and one of those works (that of Paul) almost certainly predates any of the synoptics.
In other words, Olivet was probably a discernable, yet clearly flexible, unit passed around the early church, almost certainly in oral form and possibly even in written form. (The actual setting of the teaching on Olivet may well be synoptic in origin. But I will continue to use that term for convenience.)
There is, in addition, a host of parallel and related passages within the synoptic tradition itself that serve to elucidate the Olivet logia. What I call the central passages are those that comprise the actual Olivet discourse, plus that portion of the double tradition that Matthew places on Olivet but Luke in his central section. The peripheral passages are the main parallels from other parts of the synoptic gospels.
The seven seals of Revelation 6.1-17; 8.1-6.
Other pages of interest: