I say, and with God's success: Washing is required when the glans is inserted into the vagina or anus, for both the active and passive partners. The glans is what is above the circumcision, and it is the head of the male. Washing is required if the circumcised parts meet and the glans is hidden in one of the two passages, whether ejaculation occurs or not. This is unlike when one has intercourse with a dead body, a child who is not desired, or an animal; washing is not required unless ejaculation occurs, because the cause for washing is ejaculation. Intercourse is considered equivalent to it, as it is often a cause leading to it. This causation is only realized when desire is complete, and here it is lacking. Abu Huraira (may Allah be pleased with him) said: The Messenger of Allah (peace be upon him) said: "When he sits between her four limbs and exerts himself, then washing is obligatory upon him," in Sahih al-Bukhari 1: 110, and Sahih Muslim 1: 271. In another narration: "Even if he does not ejaculate," in Sahih Muslim 1: 271. Abu Musa al-Ash'ari (may Allah be pleased with him) said: "I sought permission to enter upon Aisha (may Allah be pleased with her), and she granted me permission. I said to her: O my mother or O mother of the believers, I want to ask you about something, and I feel shy. She said: Do not be shy to ask me about what you would ask your mother who gave birth to you, for I am indeed your mother. I said: What necessitates washing? She said: The knowledgeable one has spoken. The Messenger of Allah (peace be upon him) said: When he sits between her four limbs and the circumcised parts touch, then washing is obligatory," in Sahih Muslim 1: 271, and in Sahih Ibn Khuzaymah 1: 114, and Sahih Ibn Hibban 3: 452. From Amr ibn Shu'ayb, from his father, from his grandfather (may Allah be pleased with him), he said (peace be upon him): "When the circumcised parts meet and the glans is hidden, then washing is obligatory," in Sunan Ibn Majah 1: 200. Al-Kinani said in Al-Misbah 1: 82: Its chain is weak due to the weakness of Ibn Arta'ah. Al-Tahanawi said in I'la al-Sunan 1: 195: Everything in Musnad Ahmad is acceptable, as the weak narrations therein are close to being good. In another wording: "Washing is obligatory whether he ejaculates or not," in Al-Athar 1: 13, and Musnad Abu Hanifah p. 161. From Aisha (may Allah be pleased with her), the Messenger of Allah (peace be upon him) said: "When the circumcised part exceeds the circumcised part, washing is obligatory," in Sunan al-Tirmidhi 1: 182, and he said: It is good and authentic, and in Sahih Ibn Hibban 3: 452, and Sunan al-Nasa'i 1: 108, and Muwatta Malik 1: 46. Some of the Companions denied washing except with ejaculation, so Umar sent to the wives of the Prophet (peace be upon him) and asked them about that, and they said: It requires washing. And Ali (may Allah be pleased with him) said: Do you impose the punishment for it, and do not require a sa' of water? See: Al-Waqayah p. 95, and Fath Bab al-'Inayah p. 321, and Al-Sayah p. 321, and Allah knows best.