Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Two kinds of eyes will never be touched by the Fire: an eye that spends the night guarding the Muslims in the path of Allah, and an eye that weeps out of fear of Allah."
Abu Ya'la recorded it, and al-Tabarani recorded something similar in al-Mu'jam al-Awsat, except that his wording is: "They will not see the Fire." The narrators of Abu Ya'la are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الجهاد / 9488