Abu Hurairah reported,

Someone asked, "Messenger of Allah, who will be the most fortunate of people to receive your intercession on the Day of Resurrection?"The Messenger of Allah ﷺ replied, "I thought, Abu Hurayrah, that no one would ask me about this hadith before you, given the eagerness I have seen in you for seeking knowledge. The most fortunate of people to receive my intercession on the Day of Resurrection is the one who says, 'There is no god but Allah,' sincerely from his heart or his soul."

Azami 893

Sahih

عن أبي هريرة أنه قال

قيل: يا رسول الله، من أسعد الناس بشفاعتك يوم القيامة؟ قال رسول الله ﷺ: لقد ظننت يا أبا هريرة أن لا هذا الحديث أحد أول منك، لما رأيت من حرصك على يسألني عن الحديث. أسعد الناس بشفاعتي يوم القيامة، من قال: لا إله إلا الله خالصا من قلبه أو نفسيه.

الأعظمي 893صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Faith
Chapter
Faith in the intercession of the Prophet ﷺ and others
Section
Intercession of the Prophet ﷺ for everyone who said, "There is no god but Allah," and did not associate anything with Allah, even if he committed major sins and deserved the Fire
Numbering
Jami al-Kamil 893 (2nd edition)
Azami 893