Charles Ellicott Commentary 1 Corinthians 15:31

"I protest by that glorifying in you, brethren, which I have in Christ Jesus our Lord, I die daily." — 1 Corinthians 15:31 (ASV)

I protest by your rejoicing which I have in Christ Jesus.—Better, I protest by your boast which I have in Christ Jesus. His converts are his boasting (2 Corinthians 9:3), and by the fact that they are his in the Lord, he utters the solemn assertion, I die daily. Such a life as St. Paul’s, both as regards the spiritual battles in his own soul and the ceaseless conflict with enemies around him, was indeed a daily dying (2 Corinthians 11:23–28).