Exodus 27:20 NKJV
"And you shall command the children of Israel that they bring you pure oil of pressed olives for the light, to cause the lamp to burn continually.
Pruning had to take place to get the most abundant harvest to ensure the largest quantity of oil possible.
Spiritual parallel: Pruning is getting rid of hindrances. Look at a quote from the author of Hebrews. "......let us lay aside every weight, and the sin which so easily ensnares us, and let us run with endurance the race that is set before us......"(Hebrews 12:1 NKJV)
Now let's see some quotes from letters written by the apostle Paul. Romans 13:12 NKJV:
The night is far spent, the day is at hand. Therefore let us cast off the works of darkness, and let us put on the armor of light.
Ephesians 4:22 NKJV: that you put off, concerning your former conduct, the old man which grows corrupt according to the deceitful lusts,
Colossians 3:8 NKJV: But now you yourselves are to put off all these: anger, wrath, malice, blasphemy, filthy language out of your mouth.
Look at what Jesus said. Matthew 5:29-30 NKJV: If your right eye causes you to sin, pluck it out and cast it from you; for it is more profitable for you that one of your members perish, than for your whole body to be cast into hell. And if your right hand causes you to sin, cut it off and cast it from you; for it is more profitable for you that one of your members perish, than for your whole body to be cast into hell.
Of course this is symbolic text. Jesus was talking about how serious we need to be about getting rid of things that are hurting us spiritually. He is talking about pruning.