Narrated Ibn 'Abbas (RA):

The Prophet (ﷺ) was offered to marry the daughter of Hamzah. He said, "She is unlawful to me for she is the daughter of my brother in suckling; and what is unlawful by reason of blood relationship is unlawful by reason of suckling relationship." [Agreed upon].

وَعَنِ اِبْنِ عَبَّاسٍ رَضِيَ اَللَّهُ عَنْهُمَا { أَنَّ اَلنَّبِيَّ ‏- صلى الله عليه وسلم ‏-أُرِيدُ عَلَى اِبْنَةِ حَمْزَةَ.‏ فَقَالَ: "إِنَّهَا لَا تَحِلُّ لِي; إِنَّهَا اِبْنَةُ أَخِي مِنْ اَلرَّضَاعَةِ } [1]‏ وَيَحْرُمُ مِنْ اَلرَّضَاعَةِ [2]‏ مَا يَحْرُمُ مِنْ اَلنَّسَبِ.‏ مُتَّفَقٌ عَلَيْهِ [3]‏