COMMENTARY on 37:144
Mustafa Khattab:

Translation:
he would have certainly remained in its belly until the Day of Resurrection.19
Commentary:
19   The belly of the whale would have become his grave.

 

A. Yusuf Ali:

Translation:
He would certainly have remained inside the Fish 4125 till the Day of Resurrection.
Commentary:

4125  This is just the idiom. This was to be the burial and the grave of Jonah. If he had not repented, he could not have got out of the body of the creature that had swallowed him, until the Day of Resurrection, when all the dead would be raised up.