Jami` at-Tirmidhi 3590
جامع الترمذي#3590HasanAbu Hurairah [may Allah be pleased with him] narrated that the Messenger of Allah (ﷺ) said:“No worshipper has ever said: None has the right to be worshipped but Allah (Lā ilāha illallāh)’ sincerely, except that the gates of heaven are opened for it, until it reaches to the Throne, so long as he avoids the major sins.”
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirHasan
Al-AlbaniHasan
Bashar Awad MaaroufHasan
Zubair Ali ZaiIsnaad Hasan
In-book reference: 48:221