It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever commits a sin and then knows with certainty that Allah Almighty is indeed aware of it, he is forgiven, even if he has not sought forgiveness."
No one narrated this hadith from Hamzah al-Zayyat (may Allah have mercy on him) except Ibrahim bin Harasah (may Allah have mercy on him), and Muhammad bin Ubaydah (may Allah have mercy on him) is alone in narrating it.
Hadith Referenceالمعجم الأوسط / باب العين / 4472
Hadith Gradingمحدثین:إسناده ضعيف جدًّا، فيه إبراهيم بن هراسة متروك
Hadith Takhrij«قال الهيثمي: وفيه إبراهيم بن هراسة وهو متروك «مجمع الزوائد ومنبع الفوائد، ج 10، ص 211»»