The Prophet ﷺ commanded to apply collyrium mixed with musk at the time of sleep. He said: A man who is fasting should abstain from it. Abu Dawud said: Yahya b. Ma'in said to me: This tradition about the use of collyrium is munkar (i.e. contradicts the sound traditions on the subject).
عَنِ النَّبِيِّ ﷺ أَنَّهُ أَمَرَ بِالإِثْمِدِ الْمُرَوَّحِ عِنْدَ النَّوْمِ وَقَالَ لِيَتَّقِهِ الصَّائِمُ