Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: The Messenger of Allah (peace and blessings be upon him) had himself cupped on the two veins at the sides of the neck, and gave the cupper his wage. Had it been unlawful, he (peace and blessings be upon him) would not have given it to him.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12531