Musannaf Ibn Abi Shaybah

Hazrat Qatadah says that I wrote a letter to Ibrahim asking him to inform me about the milk that establishes the prohibition of fosterage. So he wrote back to me that Hazrat Ali (may Allah be pleased with him) and Hazrat Abdullah (may Allah be pleased with him) used to say that whether the amount of suckling is little or much, the prohibition is established by it.