Know that beauty is two types: external and internal. Internal beauty is loved for itself; it is the beauty of knowledge, reason, generosity, chastity and courage. That inside beauty is what God looks at and loves in His servant. Moreover, inside beauty beautifies the external image even if it is not appealing, when the person is covered with reverence, sweetness and beautiful manners as much as his soul acquires of those features. A believer is granted reverence and beauty according to his faith, so he is revered by those who meet him and loved by those who deal with him. This is commonly observed as you can see the righteous, charitable and well-mannered man projecting the nicest impression even if he is plain in looks, especially when he has been blessed with keeping night prayers as they illuminate the face and beautify it.
Ibnul-Qayyem al-Jawzy
