Ka‘b ibn ‘Ujrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "There are certain things, the sayer of which – or the performer of which – after every prescribed prayer will never be disappointed: Tasbīh (saying 'Subhānallāh') thirty-three times, Tahmīd (saying 'Al-hamdulillāh') thirty-three times, and Takbīr (saying 'Allāhu Akbar') thirty-four times."
The Prophet (may Allah's peace and blessings be upon him) informed about certain Adhkār (regular supplications) whose sayer will never lose or regret; rather, he will attain a reward for saying such words that succeed each other and that are to be said after the obligatory prayer. These Adhkār are: "Subhānallāh" (glory be to Allah) thirty-three times, i.e., exalting Allah Almighty above any deficiency. "Al-hamdulillāh" (praise be to Allah) thirty-three times, i.e., describing Allah with complete perfection, along with loving and extolling Him. "Allāhu Akbar" (Allah is the Greatest) thirty-three times, as Allah is greater, more magnificent, and mightier than everything.