The Messenger of Allah ﷺ had himself cupped on the surface of his foot because of a pain in it while he was in the sacred state (wearing ihram). Abu Dawud said: I heard Ahmad say: "Ibn Abi 'Arubah narrated it in Mursal form". Meaning from Qatadah. (Using translation from Abū Dāʾūd 1837)  

أَنَّ رَسُولَ اللهِ ﷺ «احْتَجَمَ وَهُوَ مُحْرِمٌ عَلَى ظَهْرِ الْقَدَمِ مِنْ وَثْءٍ كَانَ بِهِ»