Albert Barnes Commentary 1 Corinthians 15:7

"then he appeared to James; then to all the apostles;" — 1 Corinthians 15:7 (ASV)

After that, He was seen of James. This appearance is not recorded by the evangelists. It is mentioned in the fragment of the apocryphal Gospel according to the Hebrews, which is, however, of no authority. It is probable that the Lord Jesus appeared often to the disciples, as He was on earth for forty days after His resurrection, and the evangelists have only mentioned the more prominent instances and enough to substantiate His resurrection.

The Fathers say this James was James the Less, the brother or first cousin of the Lord Jesus. The other James was dead when this epistle was written. This James, the author of the epistle that bears his name, was stationed in Jerusalem.

When Paul went there after his return from Arabia, he had an interview with James (Galatians 1:19, But other of the apostles saw I none, save James the Lord's brother; ). It is highly probable that Paul would state to him the vision which he had of the Lord Jesus on his way to Damascus, and that James also would state to Paul the fact that he had seen Him after He rose. This may be the reason Paul mentions this fact here, because he had it from the lips of James himself.

Then of all the apostles. By all the apostles. Perhaps it was the occasion at the Sea of Galilee, recorded in John 21:14. Or it is possible that He frequently met the apostles assembled together, and that Paul means to say that during the forty days after His resurrection, He was often seen by them.