Riyad as-Salihin 1877
'Aishah (May Allah be pleased with her) reported:
Prior to his demise, the Messenger of Allah (ﷺ) used to supplicate frequently: Subhan Allahi wa bihamdihi; Astaghfirullaha wa atubu ilaihi (Allah is free from imperfection, and I begin with praising Him. I beg forgiveness from Allah and I turn to Him in repentance." [Al-Bukhari and Muslim] .
وعن عائشة رضي الله عنها قالت‏:‏ كان رسول الله صلى الله عليه وسلم  يكثر أن يقول قبل موته ‏
"‏سبحان الله وبحمده، أستغفر الله، وأتوب إليه‏"‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏‏.‏