Sahih al-Bukhari 3255
Sahih al-Bukhari · Book 59: Beginning of Creation · The characteristics of Paradise, and the fact that it has already been created
Narrated Al-Bara (bin Azib):
حَدَّثَنَا حَجَّاجُ بْنُ مِنْهَالٍ ، حَدَّثَنَا شُعْبَةُ ، قَالَ عَدِيُّ بْنُ ثَابِتٍ أَخْبَرَنِي قَالَ سَمِعْتُ الْبَرَاءَ ـ رضى الله عنه ـ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ لَمَّا مَاتَ إِبْرَاهِيمُ قَالَ " إِنَّ لَهُ مُرْضِعًا فِي الْجَنَّةِ " .
The Prophet, after the death of his son Ibrahim, said, "There is a wet-nurse for him (i.e. Ibrahim) in Paradise."