It is narrated from a Sheikh who met the Prophet (peace be upon him) that once the Prophet (peace be upon him) heard a man reciting Surah Al-Kafirun. The Prophet (peace be upon him) said: "He has become free from shirk." Then he saw another man reciting Surah Al-Ikhlas. The Prophet (peace be upon him) said: "By its blessing, he has been forgiven."
Hadith Referenceمسند احمد / مسند المدنيين رضي الله عنهم اجمعين / 16617
Hadith Gradingحکم دارالسلام:حديث صحيح، شريك سيئ الحفظ، لكنه توبع