Except He was much more specific then what you're letting on.
Mat 12:39 But He answered and said to them, "An evil and adulterous generation seeks after a sign, and no sign will be given to it except the sign of the prophet Jonah.
Mat 12:40 For as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth.
Question: How many hours was Jonah in the fish? And did Jesus know the number of hours?
Jon_1:17 Now the LORD had prepared a great fish to swallow Jonah. And Jonah was in the belly of the fish three days and three nights.
Lol, your question betrays an utter ignorance of how Jews counted days. They didn’t count hours, any part of a day counted as one day.
So when Jesus was crucified on Friday afternoon, this was day one. Saturday was day two. And according to Luke 24, Sunday was the the third day, the day he rose from the dead.