Galatians 3:20

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

1 Timothy 2:5

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

Deuteronomy 6:4

Hear, Israel: Jehovah our God is one Jehovah;

Hebrews 8:6

But now he has got a more excellent ministry, by so much as he is mediator of a better covenant, which is established on the footing of better promises.

Hebrews 9:15

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

Hebrews 12:24

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

Genesis 15:18

On the same day Jehovah made a covenant with Abram, saying, Unto thy seed I give this land, from the river of Egypt to the great river, the river Euphrates;

Genesis 17:1-2

And Abram was ninety-nine years old, when Jehovah appeared to Abram, and said to him, I am the Almighty God: walk before my face, and be perfect.

Job 9:33

There is not an umpire between us, who should lay his hand upon us both.

Acts 12:20

And he was in bitter hostility with the Tyrians and Sidonians; but they came to him with one accord, and, having gained Blastus the king's chamberlain, sought peace, because their country was nourished by the king's.

Romans 3:29-30

Is God the God of Jews only? is he not of the nations also? Yea, of nations also:

Galatians 3:17

Now I say this, A covenant confirmed beforehand by God, the law, which took place four hundred and thirty years after, does not annul, so as to make the promise of no effect.

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 an umpire between us, who should lay his hand upon us both.
Acts 12:20
And he was in bitter hostility with the Tyrians and Sidonians; but they came to him with one accord, and, having gained Blastus the king's chamberlain, sought peace, because their country was nourished by the king's.
1 Timothy 2:5
For God is one, and the mediator of God and men one, the man Christ Jesus,

But

Galatians 3:17
Now I say this, A covenant confirmed beforehand by God, the law, which took place four hundred and thirty years after, does not annul, so as to make the promise of no effect.
Genesis 15:18
On the same day Jehovah made a covenant with Abram, saying, Unto thy seed I give this land, from the river of Egypt to the great river, the river Euphrates;
Genesis 17:1
And Abram was ninety-nine years old, when Jehovah appeared to Abram, and said to him, I am the Almighty God: walk before my face, and be perfect.
Deuteronomy 6:4
Hear, Israel: Jehovah our God is one Jehovah;
Romans 3:29
Is God the God of Jews only? is he not of the nations also? Yea, of nations also:

General references

Deuteronomy 5:3
Not with our fathers did Jehovah make this covenant, but with us, even us, those who are here alive all of us this day.
Romans 3:30
since indeed it is one God who shall justify the circumcision on the principle of faith, and uncircumcision by faith.
James 2:19
Thou believest that God is one. Thou doest well. The demons even believe, and tremble.