صحيح البخاري Sahih Bukhari كتاب الغسل The Book of Ghusl (Washing of the Whole Body)
بَابُ تَخْلِيلِ الشَّعَرِ حَتَّى إِذَا ظَنَّ أَنَّهُ قَدْ أَرْوَى بَشَرَتَهُ أَفَاضَ عَلَيْهِ:

(15) Chapter. To rub the hair thoroughly (while taking a bath) till one feels that one has made his skin wet (underneath the hair) and then one pours water over it.

2 hadith
Hadith 272
حَدَّثَنَا عَبْدَانُ ، قَالَ : أَخْبَرَنَا عَبْدُ اللَّهِ ، قَالَ : أَخْبَرَنَا هِشَامُ بْنُ عُرْوَةَ ، عَنْ أَبِيهِ ، عَنْ عَائِشَةَ ، قَالَتْ : " كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا اغْتَسَلَ مِنَ الْجَنَابَةِ غَسَلَ يَدَيْهِ وَتَوَضَّأَ وُضُوءَهُ لِلصَّلَاةِ ، ثُمَّ اغْتَسَلَ ، ثُمَّ يُخَلِّلُ بِيَدِهِ شَعَرَهُ حَتَّى إِذَا ظَنَّ أَنَّهُ قَدْ أَرْوَى بَشَرَتَهُ أَفَاضَ عَلَيْهِ الْمَاءَ ثَلَاثَ مَرَّاتٍ ، ثُمَّ غَسَلَ سَائِرَ جَسَدِهِ .
Narrated Hisham bin `Urwa: (on the authority of his father) `Aisha said, "Whenever Allah's Apostle took the bath of Janaba, he cleaned his hands and performed ablution like that for prayer and then took a bath and rubbed his hair, till he felt that the whole skin of the head had become wet, then he would pour water thrice and wash the rest of the body."
Hadith Reference Sahih Bukhari / The Book of Ghusl (Washing of the Whole Body) / Hadith: 272
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة
Hadith 273
وَقَالَتْ : كُنْتُ أَغْتَسِلُ أَنَا وَرَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مِنْ إِنَاءٍ وَاحِدٍ نَغْرِفُ مِنْهُ جَمِيعًا " .
Aisha further said, "I and Allah's Apostle used to take a bath from a single water container, from which we took water simultaneously."
Hadith Reference Sahih Bukhari / The Book of Ghusl (Washing of the Whole Body) / Hadith: 273
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة