I saw the Messenger ﷺ perform ablution. He had a Qutri turban. He inserted his hand beneath the turban and wiped over the forelock, and did not untie the turban.
رَأَيْتُ رَسُولَ اللَّهِ ﷺ يَتَوَضَّأُ وَعَلَيْهِ عِمَامَةٌ قِطْرِيَّةٌ فَأَدْخَلَ يَدَهُ مِنْ تَحْتِ الْعِمَامَةِ فَمَسَحَ مُقَدَّمَ رَأْسِهِ وَلَمْ يَنْقُضِ الْعِمَامَةَ
"I saw the Messenger of Allah performing ablution, wearing a Qatari turban. He put his hand beneath the turban and wiped the front part of his head, and he did not take the turban off."
رَأَيْتُ رَسُولَ اللَّهِ ﷺ تَوَضَّأَ وَعَلَيْهِ عِمَامَةٌ قِطْرِيَّةٌ فَأَدْخَلَ يَدَهُ مِنْ تَحْتِ الْعِمَامَةِ فَمَسَحَ مُقَدَّمَ رَأْسِهِ وَلَمْ يَنْقُضِ الْعِمَامَةَ
I saw the Messenger ﷺ perform ablution. He had a Qutri turban. He inserted his hand beneath the turban and wiped over the forelock, and did not untie the turban. (Using translation from Abū Dāʾūd 147)
رَأَيْتُ رَسُولَ اللهِ ﷺ يَتَوَضَّأُ وَعَلَيْهِ عِمَامَةٌ قَطَرِيَّةٌ فَأَدْخَلَ يَدَيْهِ مِنْ تَحْتِ الْعِمَامَةِ فَمَسَحَ مُقَدَّمَ رَأْسِهِ وَلَمْ يَنْقُضِ الْعِمَامَةَ