The Messenger of Allah ﷺ said, "There are phrases recited after every obligatory prayer whose reciter, or doer, will never be disappointed. Thirty-three glorifications of Allah, thirty-three praises of Allah, and thirty-four declarations of Allah's greatness."
عن رسول الله ﷺ قال: معقبات لا يخيب قائلهن-أو فاعلهن- دبر كل صلاة مكتوبة، ثلاث وثلاثون تسبيحة، وثلاث وثلاثون تحميدة، وأربع وثلاثون تكبيرة.
Muslim narrated it in the Book of Mosques (596), from Hasan bin Isa, from Ibn Mubarak, from Malik bin Mughul, who said, I heard Hakam bin Utayba narrating from Abdul-Rahman bin Abu Layla, from Kaab bin Ujra, and he mentioned it similarly.As for his saying "muaqqibat," Harawi said that Samura said it means glorifications performed at the end of the prayer. Abu Haytham said they are called muaqqibat because they are performed one after another. And regarding the words of Allah Almighty, "He has guardians before him and behind him" [Raad 13:11], meaning angels who succeed one another. This is what Nawawi said. "Dubr" means the end of the prayer.