Jami At Tirmidhi
3412
Sahih+2

Ka’b bin Ujrah narrated that:The Prophet said: “There are Mu’aqqibat, he who says them shall not be miserable. Glorify Allah at the end of every prayer thirty-three times, and praise him thirty-three times, and extol His greatness thirty-four times.”

SahihAhmad Muhammad Shakir
SahihAl-Albani