Then the mariners were afraid, and cried every man unto his god, and cast forth the wares that were in the ship into the sea, to lighten it of them. But Jonah had gone down into the lower part of the ship; and he had lain down, and was fast asleep.
All Commentaries on Jonah 1:5 Go To Jonah 1
Haimo of Auxerre
This is done in the greatest danger, in order that the ship, once lightened, may be borne up by the waves more easily.