And nursing is in the same position as lineage. Among those from whom we have preserved this view are 'Ata', Tawus, al-Hasan, Ibn Sirin, Makhul, Qatadah, al-Thawri, al-Awza'i, Abu 'Ubayd, Abu Thawr, and the People of Reason (Ashab al-Ra'y); we have not preserved any disagreement with them from anyone. The second category is the prohibition of combination. What is mentioned in the Book is the combination of two sisters, whether they are from lineage or nursing, whether they are free women or slave women, or one is free and the other a slave, whether they are from two parents or from one father or one mother. This applies equally to what occurs before consummation or after it, due to the generality of the verse. If he marries both in one contract, it is void, because there is no superiority of one over the other (29). This is the same whether he knew of that at the time of the contract or after it. If he marries one after the other, the marriage to the first is valid, because there is no combination involved, and the marriage to the second is invalid, because through it a combination occurs. There is no disagreement regarding this, praise be to Allah, and there is no derivation (tafri') required.

1145- Issue; he said: (What is prohibited by nursing is what is prohibited by lineage.)

Every woman prohibited due to lineage is prohibited similarly due to nursing. They are the mothers, daughters, sisters, paternal aunts, maternal aunts, nieces (brother's daughters), and nieces (sister's daughters), in the manner we explained regarding lineage, due to the saying of the Prophet (peace and blessings of Allah be upon him): "What is prohibited by nursing is what is prohibited by (1) lineage." It is agreed upon (2). In a version by Muslim: "Nursing prohibits what birth prohibits."