Sunan at-Tirmidhi (Jami-al-Tirmidhi), Chapter: Taharah (Purification)

Safwan ibn Sulaym reported on the authority of Saeed ibn Salamah of the descendants of ibn al Azraq that Mughirah ibn Abu burdah Abdad Dar informed him that he heard Sayyidina Abu Hurraira say that a man said to Allah's messenger (SAW), "O then we would go thirsty. May we make ablution with sea water?" He said ,"Its water is pure and its dead are lawful food." [Ahmed8743, Abu Dawud 83, Nisai 59, Ibn e Majah 386]