Mishkat al-Masabih 7 Fasting كتاب الصوم 54

وَعَنْ أَنَسٍ قَالَ: جَاءَ رَجُلٌ إِلَى النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: ” اشتكيت عَيْني أَفَأَكْتَحِلُ وَأَنَا صَائِمٌ؟ قَالَ: «نَعَمْ» . رَوَاهُ التِّرْمِذِيُّ وَقَالَ: لَيْسَ إِسْنَادُهُ بِالْقَوِيِّ وَأَبُو عَاتِكَةَ الرَّاوِي يضعف

Anas told of a man coming to the Prophet and saying, “I have a complaint in my eyes, so may I apply collyrium while I am fasting?” He replied, “Yes.” Tirmidhi transmitted it, saying its isnad is not strong and Abu ‘Atika the transmitter is declared to be weak.