Hadith 8:268
Abu Bakr narrated to us, he said: Sahl ibn Yusuf narrated to us, from ‘Amr, from al-Hasan, that he used to see no harm in the *muhrim* (pilgrim in state of ihram) washing his head, but he disliked that he should rub his head.
حدثنا أبو بكر قال ثنا سهل بن يوسف عن عمرو عن الحسن أنه كان لا يرى بأسا أن يغسل المحرم رأسه ويكره أن يشد ذلك رأسه