not one iota - 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.
Not even the smallest amount, as in He got not one iota of thanks for his efforts. This usage appeared in slightly different form in the New Testament (Matthew 5:18): “One jot [iota] ... shall in no wise pass from the law till all be fulfilled.” (The noun jot comes from the Greek iota.)