Sayyiduna Abu Umamah (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "Either you will straighten the rows, or your faces will be effaced; and either you will lower your gazes, or your sight will be snatched away."
Imam Ahmad and Tabarani recorded it in al-Mu'jam al-Kabir; its chain mentions that Abdullah bin Zahr narrated it from Ali bin Yazid, and both of these narrators are da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2495