Zayd bin Aslam reported,

Umar bin Khattab drank some milk and found it pleasing, so he asked the man who had given it to him where the milk had come from. The man told him, "I came upon a watering place," and he named it, "and there were camels from the camels of charity being watered. They milked some of them for me, and I put it in my waterskin. This is that milk."So Umar bin Khattab put his hand in his mouth and made himself vomit it up.

و حدثني عن مالك

عن زيد بن أسلم أنه قال

شرب عمر بن الخطاب لبنا فأعجبه فسأل الذي سقاه من أين هذا اللبن فأخبره أنه ورد على ماء قد سماه فإذا نعم من نعم الصدقة وهم يسقون فحلبوا لي من ألبانها فجعلته في سقائي فهو هذا فأدخل عمر بن الخطاب يده فاستقاءه