Mishkat al-Masabih 10 The Rites of Pilgrimage كتاب المناسك 42

وَعَنِ ابْنِ عُمَرَ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَبَّدَ رَأْسَهُ بِالْغِسْلِ. رَوَاهُ أَبُو دَاوُد

Ibn ‘Umar said that the Prophet matted his hair with ghisl (A lotion made of marsh-mallows, or lotus leaves, or fuller’s earth, or potash with water). Abu Dawud transmitted it.