The Prophet ﷺ said, "When the two circumcised parts meet, the ritual bath becomes obligatory."
حدثنا هناد حدثنا وكيع عن سفيان عن علي بن زيد عن سعيد بن المسيب
قال النبي ﷺ إذا جاوز الختان الختان وجب الغسل
Sourcing, sahih. Ahmad reported it in 6/135 from Waki, from him. Sufyan Thawri, followed by Shubah, (Ahmad 6/97) and Ismail bin Ulaya also, 6/47. This hadith has corroborating narrations, among them the preceding hadith.