ENOfficial
Anas said the Prophet (ﷺ) was not accustomed to visit an invalid till he had been ill for three days. Ibn Majah and Baihaqi, in Shu'ab al- iman, transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ أَنَسٍ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَا يَعُودُ مَرِيضًا إِلَّا بَعْدَ ثَلَاثٍ. رَوَاهُ ابْنُ مَاجَهْ وَالْبَيْهَقِيُّ فِي شُعَبِ الْإِيمَانِ
sunnah.com