Hadith on Sickness: Your illness is purification, if Allah wills

Ibn Abbas reported: If the Prophet, peace and blessings be upon him, entered the home of sick person to visit him, he would say, “It will not harm you. It is purification, if Allah wills.”

Source: Ṣaḥīḥ al-Bukhārī 5332

Grade: Sahih (authentic) according to Al-Bukhari

عَنْ ابْنِ عَبَّاسٍ رَضِيَ اللَّهُ عَنْهُمَا قَالَ كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا دَخَلَ عَلَى مَرِيضٍ يَعُودُهُ فَقَالَ لَهُ لَا بَأْسَ طَهُورٌ إِنْ شَاءَ اللَّهُ

5332 صحيح البخاري المرضى باب عيادة الأعراب