Two eyes will not be touched by the Fire: an eye which has wept out of fear of Allah, and an eye which has spent the night guarding in the cause of Allah. [At-Tirmidhi]
"«عَيْنَانِ لاَ تَمسُّهُمَا النَّار: عَيْنٌ بَكَتْ من خَشْيَة الله، وعَيْنٌ بَاتَت تَحْرُسُ في سَبِيل الله». [رواه الترمذي.]"