Aisha's account of what he repeated
She noticed he had begun saying it constantly in rukūʿ and sujūd.
سُبْحَانَكَ اللَّهُمَّ، رَبَّنَا وَبِحَمْدِكَ، اللَّهُمَّ اغْفِرْ لِي
Subḥānaka-llāhumma rabbanā wa bi-ḥamdik, Allāhumma-ghfir lī.
“Glory be to You, O Allah, our Lord, and praise. O Allah, forgive me.”
He was acting on what had been revealed to him, which he took as a sign that his time was near.
The full narration
Narrated 'Aishah (ra):The Prophet (ﷺ) used to say in his bowings and prostrations, "Subhanaka Allahumma Rabbanã wa bihamdika, Allãhumma ighfirli" (Glorified be You, O Allah, our Lord! All the praises are for You. O Allah, forgive me)
Source
Ṣaḥīḥ al-Bukhārī · 4293
Ṣaḥīḥ
- Agreed upon as authentic (al-Bukhārī / Muslim)