Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyidah Aisha (may Allah be pleased with her) that when the circumcised parts of the Prophet (peace be upon him) (and his wife) met, he would perform ghusl (ritual bath).

The Messenger of Allah (peace and blessings be upon him) said: When the circumcised parts of (a man and a woman) meet, then ghusl (ritual bath) becomes obligatory. With these words, this hadith is narrated from Lady Aisha, Abdullah bin Amr bin Al-As, and Abu Hurairah (may Allah be pleased with them) and others.