The Messenger of Allah ﷺ said, "Whoever says 'Subhan Allah' thirty-three times, 'Allahu Akbar' thirty-three times, and 'Alhamdulillah' thirty-three times, and then says, 'There is no god but Allah alone, with no partner. To Him belongs the dominion, to Him belongs all praise, and He is capable of all things,' after each prayer, his sins will be forgiven, even if they were more than the foam of the sea."
حدثنا سريج قال حدثنا فليح عن سهيل يعني ابن أبي صالح عن أبي عبيد عن عطاء بن يزيد
قال رسول الله ﷺ من سبح ثلاثا وثلاثين وكبر ثلاثا وثلاثين وحمد ثلاثا وثلاثين وقال لا إله إلا الله وحده لا شريك له له الملك وله الحمد وهو على كل شيء قدير خلف الصلاة غفر له ذنبه ولو كان أكثر من زبد البحر
Its chain of transmission is sahih. Muslim narrated it, 1/418 no. 597, in the Book of Mosques, on the recommendation of remembrance after the prayer, and Malik, 1/209. Abu Ubayd is al-Madhhiji, known by his kunya, and it is said his name was Abdul-Malik, the companion of Sulayman bin Abdullah, and he is trustworthy according to them.