Revelation 22:18-19 reads:
18) For I testify unto every man that heareth the words of the prophecy of this book [Bible], If any man shall add unto these things, God shall add unto him the plagues that are written in this book:
19) And if any man shall take away from the words of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book.
There is only ONE COVENANT! The Old Testament believers looked forward towards Jesus for salvation, and the New Testament believers looked back to Christ.
Tell you what. If you can convey why God wrote so extensively about tongues that it took Paul to write it in three chapters, and you can tell me the meaning, nature, and character of tongues, come back to me when you think you "got it" and we'll reason together.
The reason I have not divulged the phenomenon of tongues is because I wanted folks here to be like the Bereans who searched the scriptures to see if what Paul said were so.
To God Be The Glory