Al-Kāfi - Volume 6 > When a Woman Gives Birth to More than one Child
Hadith #2

عَلِيُّ بْنُ مُحَمَّدٍ رَفَعَهُ عَنْ مُحَمَّدِ بْنِ حُمْرَانَ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) قَالَ إِنَّ اللَّهَ عَزَّ وَ جَلَّ خَلَقَ لِلرَّحِمِ أَرْبَعَةَ أَوْعِيَةٍ فَمَا كَانَ فِي الْأَوَّلِ فَلِلْأَبِ وَ مَا كَانَ فِي الثَّانِي فَلِلْأُمِّ وَ مَا كَانَ فِي الثَّالِثِ فَلِلْعُمُومَةِ وَ مَا كَانَ فِي الرَّابِعِ فَلِلْخُئُولَةِ .

2. Ali ibn Muhammad has narrated from in a marfu ‘ manner from Muhammad ibn Humran who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘Allah has created four receptacles for the womb. Whatever is from the first is for the father, whatever is from the second is from the mother, whatever is from the third is from the paternal uncles and whatever is from the fourth is from the maternal uncles (in gender or shape).’”