A man came to the Messenger of Allah ﷺ and said, "Messenger of Allah, we travel by sea and carry only a small amount of water with us. If we use it for ablution, we will go thirsty. May we perform ablution with seawater?"The Messenger of Allah ﷺ replied, "Its water is pure, and what dies in it is lawful to eat."
جاء رجل إلى رسول الله ﷺ فقال: يا رسول الله! إنا نركب البحر، ونحمل معنا القليل من الماء، فإن توضأنا به عطشنا، أفنتوضأ به؟ فقال رسول الله ﷺ: هو الطهور ماؤه الحل ميتته.
Malik related it in Taharah (12), from Safwan bin Salim, from Saeed bin Salama, from the family of Bani Azraq, from Mughira bin Abu Burda, who was from Bani Abdul-Dar, and he related the hadith. Via Malik's route it was also related by Abu Dawud (83), Tirmidhi (69), Nasai (59), and Ibn Majah (386).The fact that some narrators inserted "Abu Burda" between Mughira bin Abu Burda and Abu Hurairah does not harm the soundness of the hadith, for Mughira bin Abu Burda explicitly stated that he heard directly from Abu Hurairah.Bukhari graded it sahih, as reported from him by Tirmidhi in Ilal (1361). Tirmidhi said, I said, Hushaym says in this hadith "Mughira bin Abu Barza," so Bukhari said, "He erred in it. It is actually Mughira bin Abu Burda. Hushaym makes mistakes in chains of transmission, though he is more reliable when it comes to disconnected reports."As for Tirmidhi himself, he said, hasan sahih. Ibn Khuzayma (1/59) and Ibn Hibban (1243) also graded it sahih. Hakim (1/140-142) said, "This is a foundational report with which Malik opened the book of Muwatta, and the jurists of Islam have transmitted it from his era down to our own time." This is what he said, but it is not so, rather Malik opened his book with the hadith of Jibreel concerning the times of prayer.