الإثمد
A dark mineral powder (antimony-based in classical use) applied to the eyes, recommended as a nightly practice said to strengthen sight and grow the eyelashes.
عَلَيْكُمْ بِالْإِثْمِدِ عِنْدَ النَّوْمِ، فَإِنَّهُ يَجْلُو الْبَصَرَ وَيُنْبِتُ الشَّعْرَ
“Use ithmid kohl before sleeping, for it sharpens the eyesight and helps the lashes grow.” (meaning, not a literal translation)
'Ithmid' specifically refers to a particular type of antimony-based mineral used in the Hijaz region, distinct from other historical or modern kohl formulations that may use different, sometimes unsafe, ingredients — a distinction worth keeping in mind given the caution below.
Ibn al-Qayyim describes ithmid as drying and cleansing to the eye, best applied at night when the eye is at rest. He treats it as a cosmetic-medicinal hybrid, valued in the classical tradition both for appearance and for a believed protective, strengthening effect on vision, without drawing the sharp line between the two that modern categorization might expect.
Modern medicine does not recommend applying any antimony- or lead-based substance to the eye, given well-documented heavy-metal toxicity risk, particularly for children and pregnant women — this represents one of the clearer places where historical practice and current medical safety guidance diverge.