Less than five incidents of suckling will not establish prohibition for marriage. In his Sahih, Muslim recorded that `A'ishah said, "Among the parts of the Qur'an that were revealed, is the statement, `Ten incidents of suckling establishes the prohibition (concerning marriage).' It was later abrogated with five, and the Messenger of Allah died while this statement was still recited as part of the Qur'an.''' A Hadith that Sahlah bint Suhayl narrated states that the Messenger of Allah ordered her to suckle Salim the freed slave of Abu Hudhayfah with five.'' We should assert that the suckling mentioned here must occur before the age of two, as we stated when we explained the Ayah in Surat Al-Baqarah,

﴿يُرْضِعْنَ أَوْلَـدَهُنَّ حَوْلَيْنِ كَامِلَيْنِ لِمَنْ أَرَادَ أَن يُتِمَّ الرَّضَاعَةَ﴾

((The mothers) should suckle their children for two whole years, (that is) for those (parents) who desire to complete the term of suckling) ﴿2:233﴾. The Mother-in-Law and Stepdaughter are Prohibited in Marriage Allah said next,

﴿وَأُمَّهَـتُ نِسَآئِكُمْ وَرَبَائِبُكُمُ اللَّـتِى فِى حُجُورِكُمْ مِّن نِّسَآئِكُمُ اللَّـتِى دَخَلْتُمْ بِهِنَّ فَإِن لَّمْ تَكُونُواْ دَخَلْتُمْ بِهِنَّ فَلاَ جُنَاحَ عَلَيْكُمْ﴾

(Your wives' mothers, your stepdaughters under your guardianship, born of your wives unto whom you have gone in - but there is no sin on you if you have not gone in unto them,) As for the mother of the wife, she becomes prohibited for marriage for her son-in-law when the marriage is conducted, whether the son-in-law has sexual relations with her daughter or not. As for the wife's daughter, she becomes prohibited for her stepfather when he has sexual relations with her mother, after the marriage contract is ratified. If the man divorces the mother before having sexual relations with her, he is allowed to marry her daughter. So Allah said;

﴿وَرَبَائِبُكُمُ اللَّـتِى فِى حُجُورِكُمْ مِّن نِّسَآئِكُمُ اللَّـتِى دَخَلْتُمْ بِهِنَّ فَإِن لَّمْ تَكُونُواْ دَخَلْتُمْ بِهِنَّ فَلاَ جُنَاحَ عَلَيْكُمْ﴾

(Your stepdaughters under your guardianship, born of your wives unto whom you have gone in -- but there is no sin on you if you have not gone in unto them,) to marry the stepdaughter.