It is narrated from the daughter of Abu Hakam (may Allah be pleased with her) that I heard the Prophet (peace and blessings be upon him) say: Sometimes a person comes so close to Paradise that there remains only a distance of one cubit between him and Paradise, but then he utters a word due to which he becomes as far from Paradise as the distance between Makkah and Sana'a.
Hadith Referenceمسند احمد / مسند المدنيين رضي الله عنهم اجمعين / 16610
Hadith Gradingحکم دارالسلام:إسناده ضعيف، محمد بن إسحاق مدلس، وقد عنعن