hope against hope - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Hope or wish for with little reason or justification, as in I'm hoping against hope that someone will return my wallet. This expression, based on the biblical “Who against hope believed in hope” (Romans 4:18), was first recorded in 1813.