A man asked the Messenger of Allah ﷺ, "We travel by sea and carry only a little water with us. If we use it for ablution, we go thirsty. May we perform ablution with seawater?"The Prophet ﷺ replied, "Its water is pure, and its dead creatures are lawful to eat."
حدثنا أبو سلمة 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
سأل رجل رسول الله ﷺ فقال إنا نركب البحر ونحمل معنا القليل من الماء فإن توضأنا به عطشنا أفنتوضأ من ماء البحر قال فقال النبي ﷺ هو الطهور ماؤه الحل ميتته
Its isnad is sahih. Safwan bin Salim, with the diminutive form, was Zuhri's client, the Madinan, the imam and exemplar. He narrated from Ibn Umar, Abdullah bin Jafar, and Ibn Musayab, and Malik and Darawardi narrated from him. It is said that he did not lay his side down to sleep for forty years, and it is also said that he was content and would not accept the gifts of the ruler. He was reliable and authoritative, born in the year sixty and died in the year 132.