Hadith
حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا يَزِيدُ بْنُ هَارُونَ، أَخْبَرَنَا هِشَامٌ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم احْتَجَمَ وَهُوَ مُحْرِمٌ فِي رَأْسِهِ مِنْ دَاءٍ كَانَ بِهِ .
Narrated Abdullah ibn Abbas: The Messenger of Allah (ﷺ) had himself cupped in his head when he was in the sacred state (wearing ihram due to a disease from which he was suffering)
Sahih · Al-Albani
Sunan Abi Dawud 1836 ·Book 11, Hadith 116·Also available on sunnah.com·