What are the evidences which show that Rasullullah PBUH practised cupping?
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions and all those who follow his footsteps until the Last Day.
Cupping or the Arabic word al-Hijamah (الْحِجَامَةُ) is taken from the word Hajam () which means sucking and cupping means sucking blood from the body. 
Rasullullah PBUH did cupping and he said:
خَيْرُ مَا تَدَاوَيْتُمْ بِهِ الْحِجَامَةُ
“The best medical treatments you apply are cupping…” 
The mEssenger PBUH once performed cupping and it was done by Abu Taibah. Later, the Messenger PBUH gifted him with 2 gantang of food. As for the part where one should do cupping, it is narrated from Abdullah bin Malik bin Buhainah RA, the Messenger PBUH did cupping on his head:
أنَّ رَسولَ اللَّهِ صَلّى اللهُ عليه وسلَّمَ احْتَجَمَ بلَحْيِ جَمَلٍ مِن طَرِيقِ مَكَّةَ، وهو مُحْرِمٌ، في وسَطِ رَأْسِهِ.
“God’s messenger had himself cupped from the middle of his head at Lahy Jamal (This is variously said to have been a place, a hill, or some water on the way between Mecca and Medina) on the road to Mecca when he was in the sacred state.”
There are numerous hadiths which describes cupping, among them are:
- From Anas bin malik, the Prophet PBUH said:
حجمَ أبو طيبَةَ رسولَ اللهِ صلَّى اللهُ عليهِ وسلمَ ، فأمرَ له بصاعٍ من تمرٍ ، وأمَرَ أهلَهُ أن يخفِّفُوا من خراجِهِ
“Abu Taiba cupped God’s Messenger and he ordered that sa’ of dates be given him, also ordering his people to remit some of his dues.” 
- From Abdullah bin Abbas:
حجم النبيَّ صلَّى اللهُ عليهِ وسلَّمَ عبدٌ لبني بياضةَ . فأعطاهُ النبيُّ أجرَه . وكلَّم سيدَه فخفَّفَ عنهُ من ضريبتِه ولو كان سُحتًا لم يُعطِه النبيُّ صلَّى اللهُ عليهِ وسلَّم
“The slave of Banu Bayada cupped Allah’s Apostle (ﷺ) and he gave him his wages and talked to his master and he reduced the charges, and if this earning was unlawful Allah’s Apostle (ﷺ) would not have given it.” 
- From Anas bin Malik, the Prophet PBUH said:
إنَّ أفضلَ ما تداويتُم بِه الحجامةَ أو إنَّ من أمثلِ دوائِكمُ الحجامةَ
“Cupping is the most excellent means by which you can provide medical treatment.” 
- From Abdullah bin Abbas, the Prophet PBUH said:
احتجم النبيُّ صلَّى اللهُ عليهِ وسلَّمَ في الأخدعَيْنِ وبَينَ الكَتِفَيْنِ
“The Prophet (Allah bless him and give him peace) had cupping performed between the two veins in the neck and between the shoulders.” 
- From Abdullah bin Abbas, the Messenger PBUH said:
أَنَّ النَّبِيَّ صلَّى اللهُ عَلَيْهِ وَسَلَّم احْتَجَم وَهُوَ مُحرِمٌ، وَاحْتجَم وَهُوَ صَائِمٌ
“The Prophet had himself cupped when he was wearing the ihram and also when he was fasting.” 
The Benefits of Cupping
We present here several benefits of cupping , among them are:
- Excrete toxic blood under the surface of the skin.
- Improve blood circulation and gas, bloating or flatulence problems.
- Helps improve muscle spasms.
- Helps relax tensed muscles.
- Release gas and toxins in the body.
The Ruling for Cupping
Some scholars state that it is an absolute sunnah. This means anyone who does it will be rewarded regardless of whether he needs it or not. However, cupping is an instruction for those who need it and even the Prophet PBUH said as such. If a sick person decides to do cupping and go to ask an acknowledged person to perform it for him because he is practising what is advised by the Prophet PBUH, then his action will be rewarded by Allah SWT without a doubt. While for a person who doesn’t need it, then nothing is given to him. Wallahu a’lam.
 Lihat Lisan al-Arab, 3/67-68
 Narrated by al-Bukhari (5698)
 Narrated by al-Bukhari (1960)
 Narrated by al-Tirmizi (1199)
 Narrated by al-Bukhari (1802)
 This opinion is stated by a cupping practitioner, Zahrin Zulkifli in the newspaper Berita Harian. See: https://www.bharian.com.my/bhplus-old/2016/06/163024/berbekam-buang-toksik-dalam-darah