Galatians 3:20

And a mediator is not of one, and God is one.

1 Timothy 2:5

For one God, and one mediator of God and men, the man Christ Jesus;

Deuteronomy 6:4

Hear, Israel; Jehovah our God is one Jehovah.

Hebrews 8:6

And now he has attained a more distinguished office, in how much also he is mediator of a better covenant, which was legislated upon better promises.

Hebrews 9:15

And for this he is mediator of a new covenant, that death having been, for redemption of the transgressions for the first covenant, the called might receive the promise of eternal inheritance.

Hebrews 12:24

And to Jesus the mediator of the new covenant, and to the blood of sprinkling, speaking better things than Abel.

Genesis 15:18

In that day Jehovah cut out a covenant with Abram, saying, To thy seed gave I this land from the river of Egypt, to the great river, the river Euphrates:

Genesis 17:1-2

And Abram shall be the son of ninety years and nine years: Jehovah shall be seen to Abram and will say to him, I am God Almighty; walk thou before me, and be complete.

Job 9:33

There is not between us a reprover; he will put his hand upon us two.

Acts 12:20

And Herod was fighting with violent animosity, with Tyrians and Sidonians: but they came unanimously to him, and having conciliated Blastus, him over the king's bed-chamber, they asked peace; for their country was nourished from the king's.

Romans 3:29-30

Or only the God of the Jews? and not also of the nations? Yes, also of the nations:

Galatians 3:17

And I say this, the covenant confirmed before by God in Christ, the law, having been after four hundred and thirty years, does not annul, to neglect the promise.

Treasury of Scripture Knowledge

Summary

Now a mediator is not a mediator of one, but God is one.

Bible References

A mediator is

Job 9:33
There is not between us a reprover; he will put his hand upon us two.
Acts 12:20
And Herod was fighting with violent animosity, with Tyrians and Sidonians: but they came unanimously to him, and having conciliated Blastus, him over the king's bed-chamber, they asked peace; for their country was nourished from the king's.
1 Timothy 2:5
For one God, and one mediator of God and men, the man Christ Jesus;

But

Galatians 3:17
And I say this, the covenant confirmed before by God in Christ, the law, having been after four hundred and thirty years, does not annul, to neglect the promise.
Genesis 15:18
In that day Jehovah cut out a covenant with Abram, saying, To thy seed gave I this land from the river of Egypt, to the great river, the river Euphrates:
Genesis 17:1
And Abram shall be the son of ninety years and nine years: Jehovah shall be seen to Abram and will say to him, I am God Almighty; walk thou before me, and be complete.
Deuteronomy 6:4
Hear, Israel; Jehovah our God is one Jehovah.
Romans 3:29
Or only the God of the Jews? and not also of the nations? Yes, also of the nations:

General references

Deuteronomy 5:3
Jehovah cut not out this covenant with our fathers, but with us, we, these here this day, all we living.
Romans 3:30
Since one God, who will justify circumcision of faith, and uncircumcision by faith.
James 2:19
Thou believest that there is one God; thou doest well: and the evil spirits believe, and shudder.