Proverbs 30:6
"Add thou not unto his words, lest he reprove thee, and thou be found a liar."
Cross References (ranked by relevance)
Deuteronomy 12:32
25
What thing soever I command you, observe to do it: thou shalt not add thereto, nor diminish from it.
Deuteronomy 4:2
21
Ye shall not add unto the word which I command you, neither shall ye diminish ought from it, that ye may keep the commandments of the LORD your God which I command you.
1 Corinthians 15:15
Yea, and we are found false witnesses of God; because we have testified of God that he raised up Christ: whom he raised not up, if so be that the dead rise not.