Riyad as-Salihin — Hadith #40594

And on his authority, on the authority of the Messenger of God, may God bless him and grant him peace, he said: “Whoever glorifies God thirty-three times after every prayer, praises God thirty-three times, glorifies God thirty-three times, and says at the end of a hundred: There is no god but God alone, with no partner, to Him belongs sovereignty and to Him is praise, and He is powerful over all things, his sins will be forgiven even if they are like the foam of the sea” ((Narrated by Muslim))