Al-Kāfi - Volume 4 > Disciplines to Maintain in the State of al-’Ihram
Hadith #7

7ـ حُمَيْدُ بْنُ زِيَادٍ عَنِ ابْنِ سَمَاعَةَ عَنْ غَيْرِ وَاحِدٍ عَنْ أَبَانٍ عَنْ زُرَارَةَ قَالَ سَأَلْتُ أَبَا عَبْدِ الله (عَلَيْهِ السَّلاَم) هَلْ يَحُكُّ الْمُحْرِمُ رَأْسَهُ وَيَغْتَسِلُ بِالْمَاءِ قَالَ يَحُكُّ رَأْسَهُ مَا لَمْ يَتَعَمَّدْ قَتْلَ دَابَّةٍ وَلا بَأْسَ بِأَنْ يَغْتَسِلَ بِالْمَاءِ وَيَصُبَّ عَلَى رَأْسِهِ مَا لَمْ يَكُنْ مُلَبِّداً فَإِنْ كَانَ مُلَبِّداً فَلا يُفِيضُ عَلَى رَأْسِهِ الْمَاءَ إِلاَّ مِنَ الاحْتِلامِ.

7. Humayd ibn Ziyad has narrated from ibn Sama‘ah from more than one person from Aban from Zurarah who has said the following: “I once asked abu ‘Abd Allah, ‘Alayhi al-Salam, about a man who is in the state of Ihram; if he can scratch his head and wash it with water. He (the Imam) said, ‘He can scratch his head as long as he is certain of not killing a moving thing but it is not harmful to wash with water unless one’s head is treated with talbid (a medicine against lice), in which case one must not pour water over his head except because of wet-dream.’”