‘And he said to them, “These are my words which I spoke to you, while I was yet with you, that all things must needs be fulfilled, which are written in the law of Moses, and the prophets, and the psalms, concerning me.”
The first essential ingredient of the message of the early church was that fact that what they taught was based on the Scriptures. And this was Jesus' emphasis here. He points out that while He was with them He had revealed that everything that was written about Him had to come to their full fruition. The word for ‘fulfilled' indicates being ‘brought to completion', being ‘filled full'. It is not just a question of them happening, they will happen to the full and bring God's promises and purposes to completion.
Note especially His emphasis on ‘what is written'. Then in Luke 24:45 He speaks of ‘The Writings' (the Scriptures), and again in Luke 24:46 He speaks of what is written. To Him the written word was clearly very important. He gave no place to the oral law (the traditions of the elders). In view of this we can hardly believe that the early church saw the writing down of Jesus own words as less important. It is probable therefore that they were recorded from the beginning by such people as the ex-public servant Matthew whose business record keeping had been. Those records were probably one of the sources from which Luke derived Jesus' teaching.
(When Papias said that he preferred the living voice to what was written what he, of course, meant was that he preferred going to the source rather than receiving it second hand. He wanted to hear it first hand. He was not talking about what Justin Martyr later called ‘the memoirs of the Apostles' which would be first hand).
‘Which are written in the law of Moses, and the prophets, and the psalms, concerning me.” Jesus saw the whole of the Old Testament as pointing to Himself. Compare commentary on Luke 24:27 which see for examples of His applications.
Jesus then defines the Scriptures as ‘ the law of Moses, and the prophets, and the psalms'. The first refers to the first five books of the Old Testament which were seen as the Law of Moses, the second to the prophetic writings which included Joshua to Kings excluding Ruth, and what we call the prophets from Isaiah to Malachi (excluding Lamentations). The only question is as to whether Daniel was included with the prophets or was included with the third section, the ‘holy writings'. There seem to have been differences of opinion. But whichever way it was Jesus clearly used it as Scripture, for it is the source of some of His teaching concerning the Son of Man. ‘The psalms', which were the largest book in the third section of Scripture, ‘the other writings' (often later called the hagiographa), was a title often given to the whole of those writings which consisted of the remainder of the books in the Old Testament. Thus Jesus was aligning Himself with the Jewish canon and not including the Apocrypha or the other Apocalyptic writings as Scripture.