Musnad Abu Ya'la al-Mawsili 159:114

Wahb ibn Baqiyyah narrated to us, Khalid informed us, from Suhayl, from Abu Ubayd, from Ata ibn Yazid al-Laythi, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever glorifies Allah (says SubhanAllah) after every prayer thirty-three times, and praises Allah (says Alhamdulillah) thirty-three times, and magnifies Allah (says Allahu Akbar) thirty-three times, that is ninety-nine. And he said: To complete the hundred, [he says]: 'There is no god but Allah alone, He has no partner, to Him belongs the dominion, and to Him belongs the praise, and He is capable of all things.' His sins will be forgiven, even if they were like the foam of the sea."