Riyad us Saliheen: Hadith 1419

The Messenger of Allah (ﷺ) said, "There are some words, the reciters of which will never be disappointed. These are: Tasbih

[saying 'Subhan-Allah' (Allah is free from imperfection)], thirty-three times, Tahmid

[saying 'Al-hamdu lillah' (praise be to Allah)] thirty-three times and Takbir

[saying 'Allahu Akbar' (Allah is Greatest)] thirty-four times; and these should be recited after the conclusion of every prescribed prayer."

[Muslim]