Sayyiduna Ali (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "O Ali! You have a treasure in Paradise, and you are its 'Dhu al-Qarnayn'. Do not follow one glance with another, for only the first (glance) is permitted to you."
Al-Bazzar recorded it, and at-Tabarani in al-Mu'jam al-Awsat, who added these words: "The second (glance) is not permitted to you." The narrators of at-Tabarani are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب النكاح / 7458