ʿUyūn akhbār al-Riḍā
Hadith 1919 - وَبِهذَا الإِسنادِ قالَ: قالَ رَسُولُ اللَّهِ صَلَّى اللهُعَلَيْهِ وَآلِهِ: اِختِنوا أَوْلادَكُم يَوْمَ السَّابِعِ؛ فَإِنَّهُ اَطهَرُ أَسرَعُ لِنَباتِ اللَّحْمِ.
31-19 According to the same documentation, God’s Prophet (S) said, “Circumcise your (male) children on the seventh day after birth as this would make them cleaner and speed up their growth.”