The name of God
New International Version (NIV)
14 God said to Moses, “I am who I am.[a] This is what you are to say to the Israelite s”
This name was so Holy to the Jews that they not even wanted to express it!
King James Version (KJV)
7 Thou shalt not take the name of the Lord thy God in vain; for the Lord will not hold him guiltless that taketh his name in vain.