Genesis 
17:7   And I will establish my covenant between me and thee and thy seed after thee in their generations for an everlasting covenant, to be a God unto thee, and to thy seed after thee.

 
Exodus 
34:10   And he said, Behold, I make a covenant: before all thy people I will do marvels, such as have not been done in all the earth, nor in any nation: and all the people among which thou art shall see the work of the LORD: for it is a terrible thing that I will do with thee.

Hebrews 
8:6   But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises.
7   For if that first covenant had been faultless, then should no place have been sought for the second.
8   For finding fault with them, he saith, Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah:
9   Not according to the covenant that I made with their fathers in the day when I took them by the hand to lead them out of the land of Egypt; because they continued not in my covenant, and I regarded them not, saith the Lord.
10   For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
11   And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.
12   For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more.
13   In that he saith, A new covenant, he hath made the first old. Now that which decayeth and waxeth old is ready to vanish away.



Mediator;
   one who intervenes between two persons who are at variance, with
   a view to reconcile them.

 At variance - in disagreement; in a state of dissension or
      controversy; at enmity.

 reconcile - To cause to be friendly again; to conciliate anew; to
      restore to friendship; to bring back to harmony; to cause
      to be no longer at variance; as, to reconcile persons who
      have quarreled.
      [1913 Webster]