John Calvin Reformed @genevareformer

We may learn from this verse that Jeremiah, when he observed the heavy and hard conflicts he had to undertake, was greatly disturbed; for he had not courage enough firmly and boldly to assail enemies so many and so violent.

Matthew Henry Presbyterian @wholebiblehenry

Here is, I. Jeremiah's early designation to the work and office of a prophet, which God gives him notice of as a reason for his early application to that business (Jer 1:4, Jer 1:5): The word of the Lord came to him, with a satisfying assurance to himself that it was the word of the Lord and not a delusion; and God told him, 1.

Commenting on Jeremiah 1:4-10

John Gill Reformed Baptist @doctorgill

Be not afraid of their faces,.... Their stern looks, their frowning brows, and angry countenances, which would threaten him with destruction and death: for I am with thee, to deliver thee, saith the Lord; out of their hands, when in the most imminent danger. The Targum paraphrases the words thus, "my Word shall be thine help to deliver thee:'' which is true of Christ, the essential Word of God.