Musannaf Ibn Abi Shayba 1:1380

Ibn ‘Ulayyah narrated to us, from Ayyub, from Abu Yazid al-Madani, who said: One of the fishermen narrated to me, saying: When the Commander of the Faithful, ‘Umar, arrived at al-Jar to inspect the food provisions, I said: "O Commander of the Faithful, we ride these rafts of ours and carry water with us for the journey. Some people claim that seawater does not purify." He said: "And what water is more purifying than it?"