Good advise! How about this:
John 13:27 And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly.
28Now no man at the table knew for what intent he spake this unto him.
29For some
of them thought, because Judas had the bag, that Jesus had said unto him,
Buy those things that we have need of against the feast; or, that he should give something to the poor.
30He then having received the sop went immediately out: and it was night.
..now, if the last supper was a Passover meal, why would they think Judas was going out to buy something for a meal they'd already eaten? Maybe it was ...just supper.
But here's the thing. If 3 days/3 nights are the only sign..then why do we try and say it's not 3 days 3 nights? Keeping Easter instead of Passover keeps one blind. If we would study and do the Feasts, we might get a better understanding of why we are told to do them. One for instance, why was Mary told not to touch Messiah because He'd not ascended yet..then later He's asking Thomas to touch Him? Why are we told the graves were opened even before the (John Wayne) said "He really is the Son of God"? and then they (those in the graves) did not arise until Messiah did, 3 days later. I'm just asking questions I'd wondered about for a long time. Studying the Feasts gives us answers. The answers are in the Feasts ceremonies.