Abdullah bin al-Harith narrates from Umm al-Fadl (may Allah be pleased with her) that a Bedouin came in to the Prophet (peace and blessings be upon him) while he (peace and blessings be upon him) was in my house. He said: O Prophet of Allah (peace and blessings be upon him), I have a wife, and I married another in addition to her, and my first wife thinks that she suckled my new wife once or twice. The Prophet of Allah (peace and blessings be upon him) said: "One suck or two sucks do not establish the prohibition."
Muslim narrated it from Yahya bin Yahya.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرضاع / 15628