It is narrated from Abdullah bin Mas'ud (may Allah be pleased with him): "The (relations) that are unlawful through lineage become unlawful through suckling."
This position has been transmitted to us from among the Successors from al-Qasim bin Muhammad, Jabir bin Zayd Abu al-Sha'tha', Ata', Tawus, Mujahid and al-Zuhri.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرضاع / 15618