2 Chronicles 20:15

And he said, Give ear, O Judah, and you people of Jerusalem, and you, King Jehoshaphat: the Lord says to you, Have no fear and do not be troubled on account of this great army; for the fight is not yours but God's.

1 Samuel 17:47

And all these people who are here today may see that the Lord does not give salvation by sword and spear: for the fight is the Lord's, and he will give you up into our hands.

2 Chronicles 32:7-8

Be strong and take heart; have no fear, and do not be troubled on account of the king of Assyria and all the great army with him: for there is a greater with us.

Exodus 14:13-14

But Moses said, Keep where you are and have no fear; now you will see the salvation of the Lord which he will give you today; for the Egyptians whom you see today you will never see again.

Deuteronomy 1:29-30

Then I said to you, Have no fear of them.

Deuteronomy 20:1

When you go out to war against other nations, and come face to face with horses and war-carriages and armies greater in number than yourselves, have no fear of them: for the Lord your God is with you, who took you up out of the land of Egypt.

Deuteronomy 20:4

For the Lord your God goes with you, fighting for you to give you salvation from those who are against you.

Deuteronomy 31:6

Be strong and take heart, and have no fear of them: for it is the Lord your God who is going with you; he will not take away his help from you.

Deuteronomy 31:8

It is the Lord who goes before you; he will be with you, he will not take away his help from you or give you up: so have no fear.

Joshua 11:6

And the Lord said to Joshua, Have no fear of them: for tomorrow at this time I will give them all up dead before Israel; you are to have the leg-muscles of their horses cut and their war-carriages burned with fire.

Nehemiah 4:14

And after looking, I got up and said to the great ones and to the chiefs and to the rest of the people, Have no fear of them: keep in mind the Lord who is great and greatly to be feared, and take up arms for your brothers, your sons, and your daughters, your wives and your houses.

Psalm 17:1-2

Let my cause come to your ears, O Lord, give attention to my cry; give ear to my prayer which goes not out from false lips.

Isaiah 41:10-16

Have no fear, for I am with you; do not be looking about in trouble, for I am your God; I will give you strength, yes, I will be your helper; yes, my true right hand will be your support.

Isaiah 43:1-2

But now, says the Lord your Maker, O Jacob, and your life-giver, O Israel: have no fear, for I have taken up your cause; naming you by your name, I have made you mine.

Treasury of Scripture Knowledge

Summary

And he said, Hearken ye, all Judah, and ye inhabitants of Jerusalem, and thou king Jehoshaphat, Thus saith the LORD unto you, Be not afraid nor dismayed by reason of this great multitude; for the battle is not yours, but God's.

Bible References

The battle

2 Chronicles 32:8
With him is an arm of flesh; but we have the Lord our God, helping us and fighting for us. And the people put their faith in what Hezekiah, king of Judah, said.
1 Samuel 17:47
And all these people who are here today may see that the Lord does not give salvation by sword and spear: for the fight is the Lord's, and he will give you up into our hands.

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain