Whenever the three days and three nights of Matthew 12:40 is brought up in a "discussion" with 6th day crucifixion proponents, they frequently argue that it is a common Jewish idiom for counting any part of a day as a whole day. I wonder if anyone knows of any writing from the first century or before that shows a phrase stating a specific number of days and/or a specific number of nights when it absolutely couldn't have included at least a part of each one of the specific number of days and at least a part of each one of the specific number of nights?