The Messenger of Allah ﷺ said, regarding the verse "a life of hardship" [Ta-Ha 20:124], "It refers to the punishment of the grave."
قال رسول الله ﷺ: {معيشة ضنكا} قال: عذاب القبر.
Hakim narrated it (2/381), and from him Bayhaqi in Ithbat Azab Qabr (71), from Abu Zakariya Anbari, who said, Muhammad bin Abdul-Salam narrated to us, who said, Ishaq narrated to us, who said, Nadr bin Shumayl informed us, who said, Hammad bin Salama narrated to us, from Abu Hazim Madani, from Numan bin Abu Ayyash, from Abu Saeed, who related it. He said, "Sahih according to the criterion of Muslim." Ibn Kathir said in his Tafsir, "Its chain of transmission is good." The remaining hadiths about the punishment of the grave are mentioned in the Book of Funerals.