Don't worry that a thing will or won't occur, be confident, as in I'll get there, never fear. This phrase was used by Christopher Marlowe in Doctor Faustus (c. 1590): “'Tis but a surfeit; never fear, man.”
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
Examples from the Web for never fear
"Never-fear, we will do it," he answered confidently, and that seemed to settle it.My Strangest Case