The Messenger of Allah ﷺ recited, "You who believe, fear Allah as He should be feared, and do not die except as Muslims" [Al Imran 3:102], then said, "If a single drop of Zaqqum were to fall upon the earth, it would ruin the livelihood of all the people of this world. So how will it be for the one who has no food but it?"
حدثنا محمد بن بشار حدثنا ابن أبي عدي عن شعبة عن سليمان عن مجاهد
قرأ رسول الله ﷺ {يا أيها الذين آمنوا اتقوا الله حق تقاته ولا تموتن إلا وأنتم مسلمون} ولو أن قطرة من الزقوم قطرت في الأرض لأفسدت على أهل الدنيا معيشتهم فكيف بمن ليس له طعام غيره
[Its isnad is sahih] Tirmidhi transmitted it in the description of Hell, chapter on what has been said about the description of the drink of the people of the Fire, hadith no. 2585, from the hadith of Shuba, through this same route, and he said, hasan sahih.