Why is 1 Corinthians the first place Jesus is quoted in the Bible?
1 Corinthians is the first place Jesus is quoted chronologically because the Gospels had not yet been written. Paul could not refer back to Matthew or the other Gospel writers, so before the Gospels existed he wrote the same words to the Corinthians by revelation.
Les explains that this is the first time the Lord's Supper is explained, and one commentator notes it is probably the first time Jesus is quoted chronologically in the Scriptures because the Gospels had not yet been written. Paul could not delve back to Matthew or another Gospel writer and say it came by revelation. God does everything in His own order, and before the Gospels were written, Paul wrote the very same words to the Corinthians. The passage also gives the doctrinal reason for the Lord's Supper: partaking shows forth the Lord's death, with no stipulation as to how often a church practices it.
For I have received of the Lord that which also I delivered unto you, That the Lord Jesus the same night in which he was betrayed took bread:
See the rest