ENOfficial
Abu Huraira reported God’s messenger as saying that no one will ever say sincerely, “There is no god but God” without the gates of heaven being opened for it so that it may come to the Throne, as long as he avoids major sins. Tirmidhi transmitted it, saying this is a gharib tradition.
Source: sunnah.com
Other translations
Arabic
وَعَنْ أَبِي هُرَيْرَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَا قَالَ عَبْدٌ لَا إِلَهَ إِلَّا اللَّهُ مُخْلِصًا قَطُّ إِلَّا فُتِحَتْ لَهُ أَبْوَابُ السَّمَاءِ حَتَّى يُفْضِيَ إِلَى الْعَرْشِ مَا اجْتَنَبَ الْكَبَائِرَ» . رَوَاهُ التِّرْمِذِيُّ. وَقَالَ: هَذَا حَدِيث غَرِيب
sunnah.com