זוהר בראשית — דף רמב ע”א

The matza is the sign of faith. It is called the bread of affliction, the bread of the poor, for that poverty is the poverty of exile. Whoever eats matza on the night of Passover with intention strengthens their faith. By eating the matza, we remember the exile and the Exodus from Egypt. The matza is the bread of faith, called bread of affliction because it is precisely in the humiliation of exile that faith reveals itself.