Narrated Abu Huraira:
Allah’s Messenger (ﷺ) said regarding the sea, "It's water is purifying and its dead (animals) are lawful (to eat)." [Al- Arba’a and Ibn Abu Shaiba reported it (this version is of the latter). Ibn Khuzaima and Tirmidhi graded it Sahih. It was also reported by Malik, Shafi'i and Ahmad.]
Sahih
Bulugh al-Maram, 1
In-Book Reference: Book 1, Hadith 1