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

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." 'Aisha further said, "I and Allah's Apostle used to take a bath from a single water container, from which we took water simultaneously."

حَدَّثَنَا عَبْدَانُ، قَالَ أَخْبَرَنَا عَبْدُ اللَّهِ، قَالَ أَخْبَرَنَا هِشَامُ بْنُ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ ﷺ إِذَا اغْتَسَلَ مِنَ الْجَنَابَةِ غَسَلَ يَدَيْهِ، وَتَوَضَّأَ وُضُوءَهُ لِلصَّلاَةِ ثُمَّ اغْتَسَلَ، ثُمَّ يُخَلِّلُ بِيَدِهِ شَعَرَهُ، حَتَّى إِذَا ظَنَّ أَنْ قَدْ أَرْوَى بَشَرَتَهُ، أَفَاضَ عَلَيْهِ الْمَاءَ ثَلاَثَ مَرَّاتٍ، ثُمَّ غَسَلَ سَائِرَ جَسَدِهِ. وَقَالَتْ كُنْتُ أَغْتَسِلُ أَنَا وَرَسُولُ اللَّهِ، ﷺ مِنْ إِنَاءٍ وَاحِدٍ نَغْرِفُ مِنْهُ جَمِيعًا.