Hadith 1447 a - The Book of Suckling - Sahih Muslim - صحيح مسلم - Collection of Actions, Sayings and Teachings of Prophet Muhammad (صلى الله عليه و سلم) - Kutub as-Sittah

17. The Book of Suckling - كتاب الرضاع

3) Chapter: The daughter of one's brother through breastfeeding is forbidden in marriage

Ibn Abbas (Allah be pleased with them) reported:

It was proposed that he (the Holy Prophet) be married to the daughter of Hamza, whereupon he said: She is not lawful for me for she is the daughter of my foster-brother, and that is unlawful by reason of fosterage what is unlawful by reason of genealogy.

Reference: 1447 a
English reference: Book 8, Hadith 3409
In-book reference: Book 17, Hadith 16
Grade: Sahih
Read this hadith from Darussalam Collection

3) باب تَحْرِيمِ ابْنَةِ الأَخِ مِنَ الرَّضَاعَةِ ‏

وَحَدَّثَنَا هَدَّابُ بْنُ خَالِدٍ، حَدَّثَنَا هَمَّامٌ، حَدَّثَنَا قَتَادَةُ، عَنْ جَابِرِ بْنِ زَيْدٍ، عَنِ ابْنِ، عَبَّاسٍ أَنَّ النَّبِيَّ صلى الله عليه وسلم أُرِيدَ عَلَى ابْنَةِ حَمْزَةَ فَقَالَ ‏‏ ‏.‏ "‏ إِنَّهَا لاَ تَحِلُّ لِي إِنَّهَا ابْنَةُ أَخِي مِنَ الرَّضَاعَةِ وَيَحْرُمُ مِنَ الرَّضَاعَةِ مَا يَحْرُمُ مِنَ الرَّحِمِ ‏"