475 The Messenger of Allah (peace and blessings of Allah be upon him) is reported to have said:
“If the circumcised part passes (through) the circumcised part, then bathing (ghusl) becomes obligatory.” This hadeeth was narrated by Ahmad 5/114, al-Bukhari 293 and Muslim 346 from the words of Ubayy ibn Ka’b.
Sheikh al-Albani called the hadeeth authentic. See Sahih al-Jami’ as-Saghir 475.
____________________________________________________________________________
Under the “passing” of one circumcised by another, we mean sexual intercourse, and this is the introduction of the head of the male genital organ into the woman’s vagina. See Tuhfat-ul-Awadhi
475 ( صحيح )
إذا جاوز الختان الختان فقد وجب الغسل
( حم ت ) عن عائشة ( طب ) عن أبي أمامة ورافع بن خديج ( الشيرازي في الألقاب ) عن معاذ .
Khadeeja