Who were the eyewitnesses mentioned by name who were still living to the audience of the book/letter in question? My wife and I are wracking our Brains, and we cannot remember where the reference is or who the reference is about, but there is somewhere in the New Testament that mentions people who were eyewitnesses of Jesus and that they were still among the believers at the time of the writing.  Does anyone know where this is located?
You are certainly thinking of 1 Corinthians 15: 4-7 where the Apostle St. Paul speaks about 500 eyewitnesses of which some were still living and names all the Apostles as witnesses also.


  And that he was buried, and that he rose again the third day according to the scriptures: And that he was seen of Cephas, then of the twelve: After that, he was seen of above five hundred brethren at once; of whom the greater part remain unto this present, but some are fallen asleep. After that, he was seen of James; then of all the apostles. And last of all he was seen of me also, as of one born out of due time.