It wasnarrated that Ibn 'Abbas said:
"The Messenger of Allah (ﷺ)said: 'What a good slave is the cupper. He takes away the blood,reduces pressure on the spine, and improves the eyesight.'" (ID)
English reference (ID): Vol. 4, Book 31, Hadith 3478 (ID)
Arabic reference (ID): Book 31, Hadith 3607 (ID)