2 "Every branch in Me that does not bear fruit He takes away; and every branch that bears fruit He prunes, that it may bear more fruit...
He who abides in Me, and I in him, bears much fruit...
8 "By this My Father is glorified, that you bear much fruit; so you will be My disciples.
God "prunes" every branch that bears fruit. The Greek word refers to a gardener using a knife to trim dead, sick, and bad material off of a plant. The word refers to cleaning, cutting away, and carrying away. Jesus went on to explain that if we stay close to Him, we'll bear a lot of fruit. Why? Because He will work in that Christian to purge away anything that prevents fruit. And then in verse 8, Jesus explains that only those who bear much fruit are His dsciples.
The pastor of a large and successful church had gotten saved out of an evil life. Although a new Christian, he sometimes returned to the bars he had frequented, to play pool and gamble. One night, he had his week's pay in his pocket, when he startled gambling at pool games. He got involved with a pool shark, who won the man's entire paycheck at a single game. He told us that he promised God right then and there that he would never gamble again, and he went on to become a successful preacher and soul-winner.
Chastening is painful, but it produces fruit in a Christian's life.