Exodus 16:24

And they laid it up till the morning, as Moses bade: and it did not stink, neither was there any worm therein.

Cross-reference

Exodus 16:20 shows the opposite result when manna was kept overnight in disobedience — worms and stench, contrasting with the preservation here.

Exodus 16:33 commands keeping an omer of manna as a perpetual memorial — similar preservation without spoiling, but for a different purpose.