as I live and breathe - 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.
For sure, definitely, as in As I live and breathe, I've never seen a more beautiful view. This expression is generally used to emphasize the truth of a statement and has been so used since the mid-1600s, although sometimes it was put simply as as I live. However, the complete phrase was also used early on, as in Arthur Murphy's 1756 play The Apprentice (2:1): “As I live and breathe, we shall both be taken, for heaven's sake let us make our escape.”