In hadith Riyad As-Salihin book 16, hadith 12 it mentions all the sins of a person will be forgiven even if it could cover the surface of the sea.
This would be done for the person who recites subhanallah thirty three times, alhamdulillah thirty three times, and allahu akbar 33 times, and then recites la ilaha illallahu, wahdahu la sharika lahu, lahul-mulku wa lahul-hamdu, wa Huwa ala kulli shai’in Qadir once for a total of 100 dhikr.
In Sahih Bukhari 3113, The Prophet (SAW) said, “Shall I tell you a thing which is better than what you asked me for? When you go to your beds, say: ‘Allahu Akbar (i.e. Allah is Greater)’ for 34 times, and ‘Al hamdu Li llah (i.e. all the praises are for Allah)’ for 33 times, and Subhan Allah (i.e. Glorified be Allah) for 33 times. This is better for you than what you have requested.”
Abu Hurairah (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) said, “He who recites after every prayer: Subhan-Allah (Allah is free from imperfection) thirty-three times; Al-hamdu lillah (praise be to Allah) thirty-three times; Allahu Akbar (Allah is Greatest) thirty-three times; and completes the hundred with: La ilaha illallahu, wahdahu la sharika lahu, lahul-mulku wa lahul-hamdu, wa Huwa ‘ala kulli shai’in Qadir (there is no true god except Allah. He is One and He has no partner with Him. His is the sovereignty and His is the praise, and He is Omnipotent), will have all his sins pardoned even if they may be as large as the foam on the surface of the sea.”
[Muslim]. Reference: Book 16, Hadith 12
Utter these words mindfully and Inshallah Allah will be by your side.