كتاب النكاح
16  
The Book of Marriage
(24)
Chapter: It is permissible to have intercourse with a breastfeeding woman (Ghilah), and 'Azl is disliked
(24)
باب جَوَازِ الْغِيلَةِ وَهِيَ وَطْءُ الْمُرْضِعِ وَكَرَاهَةِ الْعَزْلِ
Sahih Muslim 1442 b

Judama daughter of Wahb, sister of Ukkasha (Allah be pleased with her). reported:

I went to Allah's Messenger (ﷺ) along with some persons and he was saying: I intended to prohibit cohabitation with the suckling women, but I considered the Greeks and Persians, and saw that they suckle their children and this thing (cohabitation) does not do any harm to them (to the suckling women). Then they asked him about 'azl, whereupon he said. That is the secret (way of) burying alive, and Ubaidullah has made this addition in the hadith transmitted by al-Muqri and that is:" When the one buried alive is asked."
حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، وَمُحَمَّدُ بْنُ أَبِي عُمَرَ، قَالاَ حَدَّثَنَا الْمُقْرِئُ، حَدَّثَنَا سَعِيدُ، بْنُ أَبِي أَيُّوبَ حَدَّثَنِي أَبُو الأَسْوَدِ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، عَنْ جُدَامَةَ بِنْتِ وَهْبٍ، أُخْتِ عُكَّاشَةَ قَالَتْ حَضَرْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم فِي أُنَاسٍ وَهُوَ يَقُولُ ‏"‏ لَقَدْ هَمَمْتُ أَنْ أَنْهَى عَنِ الْغِيلَةِ فَنَظَرْتُ فِي الرُّومِ وَفَارِسَ فَإِذَا هُمْ يُغِيلُونَ أَوْلاَدَهُمْ فَلاَ يَضُرُّ أَوْلاَدَهُمْ ذَلِكَ شَيْئًا ‏"‏ ‏.‏ ثُمَّ سَأَلُوهُ عَنِ الْعَزْلِ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ ذَلِكَ الْوَأْدُ الْخَفِيُّ ‏"‏ ‏.‏ زَادَ عُبَيْدُ اللَّهِ فِي حَدِيثِهِ عَنِ الْمُقْرِئِ وَهْىَ ‏{‏ وَإِذَا الْمَوْءُودَةُ سُئِلَتْ‏}
Reference : Sahih Muslim 1442b
In-book reference : Book 16, Hadith 167
USC-MSA web (English) reference : Book 8, Hadith 3392
  (deprecated numbering scheme)