Mishkat al-Masabih
Medicine and Spells — Hadith #4376
وَعَن أبي كَبْشَة الْأَنْمَارِيِّ: أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ احْتَجَمَ عَلَى هَامَتِهِ مِنَ الشَّاةِ الْمَسْمُومَةِ قَالَ مَعْمَرٌ: فَاحْتَجَمْتُ أَنَا مِنْ غَيْرِ سُمٍّ كَذَلِكَ فِي يَافُوخِي فَذَهَبَ حُسْنُ الْحِفْظِ عَنِّي حَتَّى كُنْتُ أُلَقَّنُ فَاتِحَةَ الْكِتَابِ فِي الصَّلَاةِ. رَوَاهُ رزين
I had myself cupped like that in the middle of my head for a reason other than poison and suffered some loss of memory till I was recommended to use Fatihat al-Kitab in the prayer.
Razin transmitted it.
* An attempt was made to poison the Prophet after the conquest of Khaibar in 7 A.H., but when he had taken a mouthful of the poisoned meat he spat it out realizing that it was poisoned.