It is narrated from Hazrat Aisha (may Allah be pleased with her) that when the Prophet (peace and blessings be upon him) would sit in any gathering or perform prayer, he would say some words. Urwah says that I asked Hazrat Aisha (may Allah be pleased with her) about these words, so she said: If you say something good, it will be sealed for you until the Day of Judgment, and if you say something else, it will be an expiation for you. And those words are: "Subhanaka wa bihamdika la ilaha illa anta astaghfirullaha wa atubu ilayh."