Abu Bakr al-Siddiq said, "When we set out with the Prophet ﷺ from Mecca to Medina, we passed by a shepherd. The Messenger of Allah ﷺ had become thirsty, so I milked a small quantity of milk for him and brought it to him. He drank from it until I was content."
قال أبو بكر الصديق: لما خرجنا مع النبي ﷺ من مكة إلى المدينة مررنا براع وقد عطش رسول الله ﷺ قال: فحلبت له كثبة من لين، فأتيته بها، فشرب حتى رضيت.
Bukhari related it in the Book of Drinks (5607), and Muslim related it in the Book of Drinks (2009:90), both through the route of Shubah, from Abu Ishaq, who said, I heard Bara, and he narrated it, with the wording being Muslim's. His saying, "kuthbah," means a small amount.