It 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.
Sahih Muslim Book 1, Hadith 43
← Previous Hadith Make a profession of it that there is no god but Allah and I will bear testimony (of your being a Muslim) on the Day of judgment. He (Abu Talib) said: Were it not the fear of the Quraysh blaming me (and) saying that it was the fear of (approaching death) that induced me to do so, I would have certainly delighted your eyes. It was then that Allah revealed: " Verily thou canst not guide to the right path whom thou lovest. And it is Allah Who guideth whom He will and He knoweth best who are the guided" (xxviii-56).

Sahih Muslim Book 1, Hadith 42 Next Hadith → I heard the Messenger of Allah (ﷺ) uttering these words (as stated above).

Sahih Muslim Book 1, Hadith 44