It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) recited this verse: "Fear Allah as He should be feared" [Al Imran: 102], then said: "If a single drop of zaqqum were dripped into the seas of this world, it would ruin people's livelihoods; so what then of the one whose very food is zaqqum?"
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11022