A man asked the Messenger of Allah ﷺ, "Messenger of Allah, we travel by sea and carry only a small amount of water with us. If we use it for ablution, we go thirsty. May we perform ablution with seawater?"The Messenger of Allah ﷺ replied, "Its water is purifying, and its dead creatures are lawful to eat."
حدثنا قتيبة عن مالك ح و حدثنا الأنصاري إسحق بن موسى حدثنا معن حدثنا مالك عن صفوان بن سليم عن سعيد بن سلمة من آل ابن الأزرق أن المغيرة بن أبي بردة وهو من بني عبد الدار أخبره أنه سمع
سأل رجل رسول الله ﷺ فقال يا رسول الله إنا نركب البحر ونحمل معنا القليل من الماء فإن توضأنا به عطشنا أفنتوضأ من ماء البحر فقال رسول الله ﷺ هو الطهور ماؤه الحل ميتته
Its isnad is sahih. Abu Dawud narrated it (Book of Purification, Chapter on Wudu with Seawater, no. 83) and others narrated it from the hadith of Malik through the same route, and it is in Muwatta (1/22, Yahya's recension). Bukhari and Ibn Khuzayma graded it sahih (no. 111), as did Ibn Hibban (no. 119) and others.On this subject there is also a report from Jabir [Ibn Majah, no. 388, and Ibn Khuzayma graded it sahih (1/59, no. 112), and it has a supporting narration in Hakim (1/143)] and from Firasi [Ibn Majah, no. 387].As for the reports of Ibn Umar and Ibn Amr, I could not find them.