Sa'id bin Salmah bin Aby سعيد بن سلمة بن أبي · The Book of Purification

"A man asked the Prophet (ﷺ): 'O Messenger of Allah, we travel by sea and we take a little water with us, but if we use it for Wudu', we will go thirsty. Can we perform Wudu', with sea-water?' The Messenger of Allah (ﷺ) said: 'Its water is a means of purification and its dead meat is permissible.'"