Mark 7:10-13 (NKJV)
There are some things that don't work well together. For example, some medicines need to be taken with meals and some before eating. Some chemicals should not be mixed with other chemicals, unless you want to have a dangerous and explosive reaction. Some plants will only grow and thrive in certain environments and not in others. The same is true with the Bible, we need to make sure that we take the Bible as our standard of truth and not mix any of our own ideas with the Word of God. What God has said in His Word will have the greatest effect in our life when we don't mix it with other things.
In Mark 7 Jesus was responding to the Pharisees' criticism about the disciples eating without first ceremonially washing their hands. Jesus then made the statement about people not helping their parents because of some tradition. The Pharisees were more concerned about following man-made rules than they were about what was actually right or wrong. They had put their rules and traditions on the same, or even a higher level, than God's Word and this mixture made God's Word ineffective in their lives. Jesus did not mix God's Word with man-made traditions and He was successful in helping others.
What we think, do, and say should be based solely on the Word of God. How do we make sure we do not mix man-made rules and traditions with God's Word? The solution is simple, spend time reading and studying God's Word to be sure we know what is in it. If we find that things in our thinking, actions, and speaking do not line up with the Word of God we need to make changes in our life and not try to make an addition to the Bible to help justify why we did not receive the results that the Bible promises. When we live our life by God's Word, without mixing in anything else, will have success.