Hadith 710B

قَالَ مَالِك : سَمِعْتُ أَهْلَ الْعِلْمِ يَقُولُونَ : لَا بَأْسَ أَنْ يَغْسِلَ الرَّجُلُ الْمُحْرِمُ رَأْسَهُ بِالْغَسُولِ بَعْدَ أَنْ يَرْمِيَ جَمْرَةَ الْعَقَبَةِ ، وَقَبْلَ أَنْ يَحْلِقَ رَأْسَهُ ، وَذَلِكَ أَنَّهُ إِذَا رَمَى جَمْرَةَ الْعَقَبَةِ ، فَقَدْ حَلَّ لَهُ قَتْلُ الْقَمْلِ وَحَلْقُ الشَّعْرِ وَإِلْقَاءُ التَّفَثِ وَلُبْسُ الثِّيَابِ
Imam Malik, may Allah have mercy on him, said: I heard from the people of knowledge, they used to say: There is no harm if a man washes his head with sidr or potash, etc., after throwing pebbles at Jamrah al-Aqabah, before shaving his head, because when he has thrown the pebbles at Jamrah al-Aqabah, it becomes permissible for him to kill lice, shave his head, remove dirt, and wear clothes.
Hadith Reference موطا امام مالك رواية يحييٰ / كتاب الحج / 710B
Hadith Takhrij «فواد عبدالباقي نمبر: 20 - كِتَابُ الْحَجِّ-ح: 7»