وَعَنْهُ مُرْسَلًا قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنِ احْتَجَمَ أَوِ اطَّلَى يَوْمَ السَّبْتِ أَوِ الْأَرْبِعَاءِ فَلَا يَلُومَنَّ إِلَّا نَفْسَهُ فِي الوَضَحِ»
“If anyone has himself cupped or smeared with something on a Saturday or a Wednesday, he must blame no one but himself if he gets leprosy.” It is transmitted in Sharh as-sunna.
Mishkat al-Masabih 4358, Book 24, Medicine and Spells, Hadith 38. 1 min read