Muwatta Malik, Book 29, Hadith 106 (USC-MSA) ⓘ

Yahya related to me from Malik that he had heard that Salim ibn Abdullah and Sulayman ibn Yasar said that if a woman whose husband had died feared that an inflammation of her eyes might affect her sight or that some complaint might befall her, she should put kohl on and seek a remedy with kohl or some other cure even if it had perfume in it. Malik said, "If there is a necessity, the deen of Allah is ease."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، وَسُلَيْمَانَ بْنِ يَسَارٍ، أَنَّهُمَا كَانَا يَقُولاَنِ فِي الْمَرْأَةِ يُتَوَفَّى عَنْهَا زَوْجُهَا إِنَّهَا إِذَا خَشِيَتْ عَلَى بَصَرِهَا مِنْ رَمَدٍ أَوْ شَكْوٍ أَصَابَهَا إِنَّهَا تَكْتَحِلُ وَتَتَدَاوَى بِدَوَاءٍ أَوْ كُحْلٍ وَإِنْ كَانَ فِيهِ طِيبٌ ‏.‏ قَالَ مَالِكٌ وَإِذَا كَانَتِ الضَّرُورَةُ فَإِنَّ دِينَ اللَّهِ يُسْرٌ ‏.‏