Albert Barnes Commentary 1 Kings 22:27

"and say, Thus saith the king, Put this fellow in the prison, and feed him with bread of affliction and with water of affliction, until I come in peace." — 1 Kings 22:27 (ASV)

Feed him with bread of affliction... Micaiah is to be put in prison once more, but, to punish him for his uncomplying spirit, on a poorer and scantier diet than he had previously been allowed. This is to continue until Ahab returns in peace. Ahab introduces this expression purposely to show his complete disbelief in Micaiah’s prophecy.