Matthew 28:20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.
John Gill Commentary:
whatsoever I have commanded you;
every thing that Christ has commanded, be it what it will, and nothing else;
for Christ’s ministers are not to teach for doctrines the commandments of men;
or enjoin that on the churches, which is of their own, or other men’s devising, and was never ordered by Christ;
John 17:17 Sanctify them through thy truth: thy word is truth.