The breast milk belongs to the sire
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، قَالَتْ أَتَانِي عَمِّي مِنَ الرَّضَاعَةِ أَفْلَحُ بْنُ أَبِي قُعَيْسٍ يَسْتَأْذِنُ عَلَىَّ بَعْدَ مَا ضُرِبَ الْحِجَابُ فَأَبَيْتُ أَنْ آذَنَ لَهُ حَتَّى دَخَلَ عَلَىَّ النَّبِيُّ ـ صلى الله عليه وسلم ـ فَقَالَ " إِنَّهُ عَمُّكِ فَأْذَنِي لَهُ " . فَقُلْتُ إِنَّمَا أَرْضَعَتْنِي الْمَرْأَةُ وَلَمْ يُرْضِعْنِي الرَّجُلُ قَالَ " تَرِبَتْ يَدَاكِ أَوْ يَمِينُكِ " .
It was narrated that 'Aishah said: “My paternal uncle through breastfeeding, Aflah bin Abu Qu'ais, came and asked permission to visit me, after the ruling on veiling had been enjoined, and I refused to let him in, until the Prophet (ﷺ) came in and said: 'He is your paternal uncle; let him in.' I said: 'But it is the woman who breastfed me; the man did not breastfeed me.' He said: 'May your hands be rubbed with dust', or: 'May your right hand be rubbed with dust!”