Mark 14:38 in the King James Version
Watch ye and pray, lest ye enter into temptation. The spirit truly is ready, but the flesh is weak.
Context
37 He came and found them sleeping, and said to Peter, “Simon, are you sleeping? Couldn’t you watch one hour?
38 Watch and pray, that you may not enter into temptation. The spirit indeed is willing, but the flesh is weak.”
39 Again he went away and prayed, saying the same words.