Musannaf Ibn Abi Shayba 1:1819

Abu Bakr narrated to us, he said: Mu'tamir ibn Sulayman narrated to us, from Salim ibn Abi al-Dhayyal, from al-Hasan, regarding a woman whose garment is touched by her milk: "Should she pray without washing her garment?" He said: "There is nothing impure in her milk."