The first occurance of this term is just after Adam sinned. Genesis 3:10 He answered, “I heard you in the garden, and I was afraid because I was naked; so I hid.”
Second is when God telling Abraham Genesis 15:1 “After this, the word of the Lord came to Abram in a vision: “Do not be afraid, Abram. I am your shield, your very great reward.””
Exodus 20:20 “Moses said to the people, “Do not be afraid. God has come to test you, so that the fear of God will be with you to keep you from sinning.””