Musnad Ahmad 920:17

Abdullah narrated to us, Hajjaj ibn Yusuf al-Sha'ir narrated to us, he said: Wahb ibn Jarir narrated to me, I asked him, my father narrated to us, he said: I heard Ayyub narrating from Ibn Jubayr, from Ibn Abbas, from Ubayy ibn Ka'b: That when Gabriel struck Zamzam with his heel, the mother of Ishmael began gathering the sand. The Prophet, may Allah bless him and grant him peace, said: "May Allah have mercy on Hajar, the mother of Ishmael; had she left it, it would have been a flowing spring."