Charles Ellicott Commentary Isaiah 41:10

"Fear thou not, for I am with thee; be not dismayed, for I am thy God; I will strengthen thee; yea, I will help thee; yea, I will uphold thee with the right hand of my righteousness." — Isaiah 41:10 (ASV)

Fear you not ... —The thought of the election of God gives a sense of security to His chosen.

I will strengthen you. —The verb unites with this meaning (Psalms 89:21) the idea of attaching to oneself, or choosing, as in Isaiah 44:14.