Isaiah 41:10

“Fear not, for I am with you; be not dismayed, for I am your God; I will strengthen you, I will help you, I will uphold you with my righteous right hand.”

Where it comes from

God speaks these words to Israel in exile, a people who had every reason to be afraid: far from home, surrounded by stronger nations, unsure they would ever go back. The command not to fear comes with five promises in a row, and every one of them starts with "I will."

What it means

Scripture says "do not fear" or "fear not" well over a hundred times, and this is the version most people memorize. Notice it never says the scary thing is not real. It says who is standing next to you while it is. Strength, help and a hand that holds you up are not things you have to produce. They are things He supplies.