In order for a Muslim to be unlawful to marry or have sexual relation with a Muslima, she just breastfeed him five to ten times
1. [Sahih Muslim 8.3422 or 1452b]
‘Amra reported that she heard ‘A’isha (Allah he pleased with her) discussing fosterage which (makes marriage) unlawful; and she (‘A’isha) said: There was revealed in the Holy Qur’an ten clear sucklings, and then five clear (sucklings).
2. [Sahih Muslim 8:3424 or 1453a]
A’isha (Allah be pleased with her) reported that Sahla bint Suhail came to Allah’s Apostle (may peace be eupon him) and said: Messengerof Allah, I see on the face of Abu Hudhaifa (signs of disgust) on entering of Salim (who is an ally) into (our house), whereupon Allah’s Apostle (ﷺ) said: Suckle him. She said: How can I suckle him as he is a grown-up man? Allah’s Messenger (ﷺ) smiled and said: I already know that he is a young man. ‘Amr has made this addition in his narration: that he [Salim] participated in the Battle of Badr and in the narration of Ibn ‘Umar (the words are): Allah’s Messenger (ﷺ) laughed.
3. [Sahih Muslim 8:3425 or 1453d]
‘A’isha (Allah be pleased with her) reported that Salim, the freed slave of Abu Hadhaifa, lived with him and his family in their house. She (i. e. the daughter of Suhail came to Allah’s Apostle (may peace be upon him) and said: Salim has attained (puberty) as men attain, and he understands what they understand, and he enters our house freely, I, however, perceive that something (rankles) in the heart of Abu Hudhaifa, whereupon Allah’s Apostle (may peace be upon him) said to her: Suckle him and you would become unlawful for him, and (the rankling) which Abu Hudhaifa feels in his heart will disappear. She returned and said: So I suckled him, and what (was there) in the heart of Abu Hudhaifa disappeared.
4. [Sahih Muslim 8:3426 or 1453c]
Ibn Abu Mulaika reported that al-Qasim b. Muhammad b. Abu Bakr had narrated to him that ‘A’isha (Allah be pleased with her) reported that Sahla bint Suhail b. ‘Amr came to Allah’s Apostle (ﷺ) and said: Messenger of Allah, Salim (the freed slave of Abu Hudhaifa) is living with us in our house, and he has attained (puberty) as men attain it and has acquired knowledge (of the sex problems) as men acquire, whereupon he said: Suckle him so that he may become unlawful (in regard to marriage) for you He (Ibn Abu Mulaika) said: I refrained from (narrating this hadith) for a year or so on account of fear. I then met al-Qasim and said to him: You narrated to me a hadith which I did not narrate (to anyone) afterwards. He said: What is that? I informed him, whereupon he said: Narrate it on my authority that ‘A’isha (Allah be pleased with her) had narrated that to me.
5. [Sahih Muslim 8:3427 or 1453d]
Umm Salama said to ‘A’isha (Allah be pleased with her): A young boy who is at the threshold of puberty comes to you. I, however, do not like that he should come to me, whereupon ‘A’isha (Allah be pleased with her) said: Don’t you see in Allah’s Messenger (ﷺ) a model for you? She also said: The wife of Abu Hudhaifa said: Messenger of Allah, Salim comes to me and now he is a (grown-up) person, and there is something that (rankles) in the mind of Abu Hudhaifa about him, whereupon Allah’s Messenger (ﷺ) said: Suckle him (so that he may become your foster-child), and thus he may be able to come to you (freely).
6. [Sahih Muslim 8.3428 or 1453e]
Zainab daughter of Abu Salama reported: I heard Umm Salama, the wife of Allah’s Apostle (may peace be upon himy, saying to ‘A’isha: By Allah, I do not like to be seen by a young boy who has passed the period of fosterage, whereupon she (‘A’isha) said: Why is it so? Sahla daughter of Suhail came to Allah’s Messenger (ﷺ) and said: Allah’s Messenger, I swear by Allah that I see in the face of Abu Hudhaifa (the signs of disgust) on account of entering of Salim (in the house), whereupon Allah’s Messenger (ﷺ) said: Suckle him. She (Sahla bint Suhail) said: He has a heard. But he (again) said: Suckle him, and it would remove what is there (expression of disgust) on the face of Abu Hudhaifa. She said: (I did that) and, by Allah, I did not see (any sign of disgust) on the face of Abu Hudhaifa.
7. [Sahih Muslim 8:3429 or 1454]
Umm Salama, the wife of Allah’s Apostle (ﷺ), used to say that all wives of Allah’s Apostle (ﷺ) disclaimed the idea that one with this type of fosterage (having been suckled after the proper period) should come to them. and said to ‘A’isha: By Allah, we do not find this but a sort of concession given by Allah’s Messenger (ﷺ) only for Salim, and no one was ging to be allowed to enter (our houses) with this type of fosterage and we do not subscribe to this view.
8. [Al-Muwatta 30:12]
Yahya related to me from Malik from Ibn Shihab that he was asked about the suckling of an older person. He said, ”Urwa ibn az-Zubayr informed me that Abu Hudhayfa ibn Utba ibn Rabia, one of the companions of the Messenger of Allah, may Allah bless him and grant him peace, who was present at Badr, adopted Salim (who is called Salim, the mawla of Abu Hudhayfa) as the Messenger of Allah, may Allah bless him and grant him peace, adopted Zayd ibn Haritha. He thought of him as his son, and Abu Hudhayfa married him to his brother’s sister, Fatima bint al-Walid ibn Utba ibn Rabia, who was at that time among the first emigrants. She was one of the best unmarried women of the Quraysh. When Allah the Exalted sent down in His Book what He sent down about Zayd ibn Haritha, ‘Call them after their true fathers. That is more equitable in the sight of Allah. If you do not know who their fathers were then they are your brothers in the deen and your mawali,’ (Sura 33 ayat 5) people in this position were traced back to their fathers. When the father was not known, they were traced to their mawla. “Sahla bint Suhayl who was the wife of Abu Hudhayfa, and one of the tribe of Amr ibn Luayy, came to the Messenger of Allah, may Allah bless him and grant him peace, and said, ‘Messenger of Allah! We think of Salim as a son and he comes in to see me while I am uncovered. We only have one room, so what do you think about the situation?’ The Messenger of Allah, may Allah bless him and grant him peace, said, ‘Give him five drinks of your milk and he will be mahram by it.’ She then saw him as a foster son. A’isha umm al-muminin took that as a precedent for whatever men she wanted to be able to come to see her. She ordered her sister, Umm Kulthum bint Abi Bakr as-Siddiq and the daughters of her brother to give milk to whichever men she wanted to be able to come in to see her. The rest of the wives of the Prophet, may Allah bless him and grant him peace, refused to let anyone come in to them by such nursing. They said, ‘No! By Allah! We think that what the Messenger of Allah, may Allah bless him and grant him peace, ordered Sahla bint Suhayl to do was only an indulgence concerning the nursing of Salim alone. No! By Allah! No one will come in upon us by such nursing!’ “This is what the wives of the Prophet, may Allah bless him and grant him peace, thought about the suckling of an older person.”
9. [Al-Muwatta 30:17]
Yahya related to me from Malik from Abdullah ibn Abi Bakr ibn Hazm from Amra bint Abd ar-Rahman that A’isha, the wife of the Prophet, may Allah bless him and grant him peace, said, “Amongst what was sent down of the Qur’an was ‘ten known sucklings make haram’ – then it was abrogated by ‘five known sucklings’. When the Messenger of Allah, may Allah bless him and grant him peace, died, it was what is now recited of the Qur’an.” Yahya said that Malik said, “One does not act on this.”
10. [Sunan Ibn Majah 3:9:1942]
It was narrated that ‘Aishah said: “Once of the things that Allah revealed in the the Qur’an and then abrogated was that nothing makes marriage prohibited except ten breastfeedings or five well-known breastfeedings.”
11. [Sunan Ibn Majah 3:9:1944]
It was narrated that ‘Aishah said: “The Verse of stoning and of breastfeeding an adult ten times was revealed, and the paper was with me under my pillow. When the Messenger of Allah died, we were preoccupied with his death, and a tame sheep came in and ate it.” These verses were abrogated in recitation but not ruling. Other ahadith establish the number for fosterage to be 5.
12. [Sunan an-Nasa’i 3311]
Sa’eed narrated from Qatadah: “We wrote to Ibrahim bin Yazid An-Nakha’i asking him about breast-feeding. He wrote back saying that Shuraih had narrated that ‘Ali and Ibn Mas’ud used to say: ‘A little or a lot of breast-feeding makes marriage prohibited.'” In his book, it said that Abu Ash-Sha’tha’ Al-Muharibi narrated that ‘Aishah had told him that the Prophet of Allah used to say: “Suckling (Al-Khatfah) once or twice does not make (marriage) prohibited.”