Jeremiah 1:17
17 “But you, Jeremiah, get yourself ready! Go and tell these people everything I instruct you to say. Do not be terrified of them, or I will give you good reason to be terrified of them. 18 I, the Lord, hereby promise to make you as strong as a fortified city, an iron pillar, and a bronze wall. You will be able to stand up against all who live in the land, including the kings of Judah, its officials, its priests, and all the people of the land. 19 They will attack you but they will not be able to overcome you, for I will be with you to rescue you,” says the Lord.
Acts 18:9
8 Crispus, the president of the synagogue, believed in the Lord together with his entire household, and many of the Corinthians who heard about it believed and were baptized. 9 The Lord said to Paul by a vision in the night, “Do not be afraid, but speak and do not be silent 10 because I am with you, and no one will assault you to harm you because I have many people in this city.” 11 So he stayed there a year and six months, teaching the word of God among them.
Notes and References
"... Although Essene texts and some other early Jewish sources sometimes linked evil behaviors with pervasive evil spirits, in Greek “spirit of” often meant simply “attitude of.” The exhortation not to be afraid was one of the most prominent biblical assurances from God (e.g., Genesis 26:24; Jeremiah 1:8) and was a customary expression of assurance from others as well (Gen 43:23). Although Timothy may have been “timid,” one should not therefore assume that this was his unique problem, as some interpreters have (compare Acts 18:9; 1 Corinthians 2:3) ..."
Keener, Craig S. The IVP Bible Background Commentary: New Testament (p. 617) InterVarsity Press, 2014