Rasulullah (sallallahu ‘alaihi wasallam) then asked, “Does she have any milk?” Ummu Ma’bad replied, “How can she have milk in this condition?” Rasulullah (sallallahu ‘alaihi wasallam) then said, “Do I have your permission to milk it?” She replied, “May my parents be sacrificed for you! If it has any milk, then you may certainly milk it.”
Rasulullah (sallallahu ‘alaihi wasallam) then recited bismillah and placed his blessed hand over its udders which miraculously began to fill with milk. Rasulullah (sallallahu ‘alaihi wasallam) then commenced milking the goat. A large container, from which about eight to ten people could satiate themselves, was filled with its milk.
Rasulullah (sallallahu ‘alaihi wasallam) first offered the milk to Ummu Ma’bad, and she drank to her fill. Rasulullah (sallallahu ‘alaihi wasallam) then offered the milk to his companions, and he himself drank at the end.
Rasulullah (sallallahu ‘alaihi wasallam) then milked the goat again until the container was once more brimming with milk. He then handed the container of milk to Ummu Ma’bad, and after accepting her Bay’ah (pledge of allegiance), he resumed his journey to Madinah Munawwarah.
In the evening, when Abu Ma’bad returned home from the jungle after grazing the goats, he noticed a large container of milk lying at their tent. He was extremely surprised and asked, “Where did this milk come from, O Ummu Ma’bad? This goat did not possess a drop of milk!” She replied, “Today, an exceptionally blessed man happened to pass this way. By Allah! All of this milk is the result of his barakah (blessings).” She then told her husband what had transpired.
After hearing the incident, Abu Ma’bad said, “Tell me more about this man.” Ummu Ma’bad then explained the description of the blessed countenance of Rasulullah (sallallahu ‘alaihi wasallam), together with his nobility, respect, awe-inspiring nature and dignity.
Hearing the description, Abu Ma’bad remarked, “I now know who you are speaking about! By Allah! This is the same man from the Quraish tribe (who people speak about). I will certainly present myself before him as well.”
(Extracted from Seeratul Mustafa 1/387-388)