Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) states that the Prophet (peace and blessings be upon him) asked a man: Did you do such-and-such (that is, a sinful deed)? He replied: No! By the One besides whom there is no deity, O Messenger of Allah, I did not do it. The Prophet (peace and blessings be upon him) said: Yes, you did do it, but you have been forgiven because of sincerity (that is, reciting the declaration of Tawhid).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأذكار / 16809
Hadith Gradingمحدثین:إسنادہ ضعیف جدا
Hadith Takhrij«اخرجه احمد فى المسند (5361) ، أخرجه مسند أحمد برقم: 5950، 5338»