Musannaf Ibn Abi Shayba 36:308

Abu Usama narrated to us, from Zakariya, from Abu Ishaq, from al-Bara’, who said: We arrived on the day of al-Hudaybiyyah, and we found that the first of the people had drunk its water. The Prophet, may Allah bless him and grant him peace, sat by the well, then he called for a bucket from it. He took what remained of it, then he spat into it, and he supplicated to Allah, so its water increased until the people were quenched from it.