Musannaf Ibn Abi Shayba 1:1509

Hushaym narrated to us, he said: Husayn informed us, from Ikrimah, that Umar ibn al-Khattab came upon one of the cisterns and wanted to perform ablution and drink. The people of the cistern said: "Dogs and beasts of prey lap from it." Umar said: "They have what they lapped into their bellies." He then drank and performed ablution.