Salah bin Abi Maryam صالح بن أبي مريم الضبعي - أبو الخليل · The Book of Marriage

"What becomes unlawful (for marriage) through breast-feeding is that which becomes unlawful through lineage."

"Why do you do that?" We said: "A man may have a wife, and he has intercourse with her, but he does not want her to get pregnant, or he may have a concubine, and he has intercourse with her, but he does not want her to get pregnant." He said: "It does not make any difference if you do that, for it is the matter of Al-Qadr."