Ka’b ibne-Ujrah Radiyallahu Anhu narrates

Ka’b ibne-Ujrah Radiyallahu Anhu narrates that Rasulullah Sallallhu Alaihi Wa Sallam said: Some phrases, when said after Salat, are such that whoever says them will never be disappointed. These are Subhanallah (Glory be to Allah Who is above all faults) 33 times, Alhamdulillah (Praise be to Allah) 33 times and Allahuakbar (Allah is the Greatest) 34 times after every obligatory Salat. (Muslim)