Sahih Muslim 136
صحيح مسلم#136SahihIt is narrated on the authority of 'Uthman that the Messenger of Allah (ﷺ) said. He who died knowing (fully well) that there is no god but Allah entered Paradise
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 1:43