Hadithcore
Mishkat al-Masabih, 1616

Abu Sa'id and Abu Huraira reported God's messenger as saying, “Recite to those of you who are dying, ‘There is no god but God. ’ ” Muslim transmitted it.

عَنْ أَبِي سَعِيدٍ وَأَبِي هُرَيْرَةَ قَالَا: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لَقِّنُوا مَوْتَاكُمْ لَا إِلَهَ إِلَّا اللَّهُ» . رَوَاهُ مُسْلِمٌ

References1 variant
In-Book Reference
Book 5, Hadith 92