Sheikh al-Sharîf Hamzah al-Fa`r, professor at Umm al-Qurâ University
Kohl is preferred for women. It is part of their beautification. Women are encouraged to beautify themselves as part of what it means for them to live with their husbands in accordance with customary goodness. Allah says: “Live with them on the footing of kindness and equity.” [Sûrah al-Nisâ’: 19]
It is also permissible for the unmarried woman this is also part of the recommended beautification. Allah describes the woman as: “…one brought up among adornments” [Sûrah al-Zukhruf: 18]
The Prophet (peace be upon him) encouraged women to use pigments like henna.
In another hadîth, the Prophet (peace be upon him) forbade the widow from using kohl during her period of mourning. This tells us that kohl is something woman may use under normal circumstances.
In the case of men, there is disagreement among people of knowledge about the use of kohl. Some scholars look upon it favorably without applying any restrictions upon its use. Others distinguish between young and old men saying that it is disliked for young men and permitted for older men.
However, we can say that the use of kohl for men is permissible because the Prophet (peace be upon him) used to use it.
Source: Islam Today