Jamieson, Fausset and Brown on 1 Corinthians 15:31

31. by your rejoicing--by the glorying which I have concerning you, as the fruit of my labors in the Lord. Some of the earliest manuscripts and fathers read "our," with the same sense. Bengel understands "your rejoicing," to be the enjoyable state of the Corinthians, as contrasted with his dying daily to give his converts rejoicing or glorying (1Co 4:8; 2Co 4:12, 15; Ep 3:13; Php 1:26). But the words, "which I have," favor the explanation--"the rejoicing which I have over you." Many of the oldest manuscripts and Vulgate insert "brethren" here.

I die daily--This ought to stand first in the sentence, as it is so put prominently forward in the Greek. I am day by day in sight of death, exposed to it, and expecting it (2Co 4:11, 12; 1:8, 9; 11:23).