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 <i>Shu'ab al- iman</i>, transmitted it.

وَعَنْ أَنَسٍ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَا يَعُودُ مَرِيضًا إِلَّا بَعْدَ ثَلَاثٍ. رَوَاهُ ابْنُ مَاجَهْ وَالْبَيْهَقِيُّ فِي شُعَبِ الْإِيمَانِ