Please do not claim you know how Jesus was using the phrase! All we have is the text.
I showed how He could have been using the phrase. As for four days, do you have a passage that indicates it might not have been four days including inclusive counting and part day counting? The counting method in use, as demonstrated by scripture, tells us four days could be as short as a little over two days, a small part of day one and four along with two full days. On the other hand it could be as long as four full days. Nothing I have presented contradicts this understanding. And I think someone in a tomb for four or nearly four days would "stinkth."
I didn't say nor did I claim to know how Jesus was using it, I said to determine how He used you must compare scripture for scripture. If the use in the Hebrew in Jonah was literal 3 days and 3 nights then Jesus in using the reference would have been showing His use, if it were a colloquialism in Jonah then by all means He was using colloquialism.
Do you have passages referencing this, to prove it a colloquialism? Can you say that the Jonah reference had nothing to do with the prophecy? My point is if you can determine the use of the term in Jonah then you know what Jesus meant, until then we are all speculating.