Luke 5:36-37, "And he spake a parable unto them; No man putteth a piece of a new garment upon an old; if otherwise, then both the new maketh a rent, and the piece that was taken out of the new agreeth not with the old. And no man putteth new wine into old bottles; else the new wine will burst the bottles, and be spilled, and the bottles shall perish."
MATTHEW 9:11-17, MARK 2:16-22, LUKE 5:30-39
These two parables are in response to the scribes' and Pharisees' criticism (v. 30) and the question from John's disciples about why Jesus didn't act according to their religious traditions and expectations (Matthew 9:14; Mark 2:18). The gist of these parables was to show that Jesus came to do a new thing that would not mix with the old covenant ways that were familiar to people (Isaiah 43:18-19; Jeremiah 31:31-34; Hebrews 8:7-13).
A new cloth sown on an old garment in Jesus' day would shrink the first time it was washed. Then it would tear away from the old garment that had already shrunk, making the hole worse. This illustrates that Jesus did not come to patch up the old Mosaic covenant, but to replace it (Hebrews 7:18-19).
Also, new wine (not yet fermented) had to be put into new or reconditioned wineskins to allow for the expansion of gases within the skin as the result of the fermentation process. Otherwise, an old wineskin that had already been stretched by use would simply burst and all the wine would run out. The Old Testament laws could never stretch enough to accommodate the New Testament truths of mercy and grace (Hebrews 10:1-10). Jesus set us free from the judgment of the Old Testament laws (Romans 6:14; 7:1-4; 8:2; 10:3-4; Galatians 3:12-14, 23-24; 5:4; Philippians 3:9).
These religious scribes and Pharisees (Luke 5:30) were making the terrible mistake of trusting in their own efforts to produce their right standing (righteousness) with God. Jesus did not come to accept our sacrificial acts, but to make Himself a sacrifice for our sins. He did all this to give us new life in Him. Thank Him for His grace today.