To use (hair) oil for the Friday prayer
حَدَّثَنَا أَبُو الْيَمَانِ، قَالَ أَخْبَرَنَا شُعَيْبٌ، عَنِ الزُّهْرِيِّ، قَالَ طَاوُسٌ قُلْتُ لاِبْنِ عَبَّاسٍ ذَكَرُوا أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " اغْتَسِلُوا يَوْمَ الْجُمُعَةِ وَاغْسِلُوا رُءُوسَكُمْ وَإِنْ لَمْ تَكُونُوا جُنُبًا، وَأَصِيبُوا مِنَ الطِّيبِ ". قَالَ ابْنُ عَبَّاسٍ أَمَّا الْغُسْلُ فَنَعَمْ، وَأَمَّا الطِّيبُ فَلاَ أَدْرِي.
Narrated Tawus: I said to Ibn `Abbas, "The people are narrating that the Prophet (ﷺ) said, 'Take a bath on Friday and wash your heads (i.e. take a thorough bath) even though you were not Junub and use perfume'." On that Ibn `Abbas replied, "I know about the bath, (i.e. it is essential) but I do not know about the perfume (i.e. whether it is essential or not.)