The Prophet ﷺ was approached by some men who fished in the sea. They said, "Messenger of Allah, we travel on rafts and carry only a small amount of fresh water with us. If we drink from it, we have nothing left for ablution, and if we use it for ablution, we have nothing left to drink. May we perform ablution with seawater?"The Prophet ﷺ replied, "Yes. Its water is pure, and what dies in it is lawful to eat."
حدثنا حسين قال حدثنا أبو أويس حدثنا صفوان بن سليم مولى حميد بن عبد الرحمن بن عوف عن سعيد بن سلمة بن الأزرق المخزومي عن المغيرة بن أبي بردة أحد بني عبد الدار بن قصي
عن النبي ﷺ أنه جاءه ناس صيادون في البحر فقالوا يا رسول الله إنا أهل أرماث وإنا نتزود ماء يسيرا إن شربنا منه لم يكن فيه ما نتوضأ به وإن توضأنا لم يكن فيه ما نشرب أفنتوضأ من ماء البحر فقال النبي ﷺ نعم فهو الطهور ماؤه الحل ميتته
Its isnad is sahih. It was mentioned previously at 7232. It was also narrated by Abu Dawud 1/83, number 21, in the chapter on purification, on performing wudu with seawater, and by Tirmidhi 1/101, number 69, similarly, and by Nasai 1/50, number 59, and by Malik 2/495, number 12, in the chapter on hunting, on what has been said about hunting in the sea, and by Ibn Khuzayma 1/59, number 111, and by Ibn Hibban 60, number 119, and by Hakim 1/141.9075m - Ibn Mahdi narrated to us, from Malik, who said, "Mughira bin Abu Burda."Sahih (9075m). Its isnad is sahih. This is an isnad through another route in which Imam Ahmad indicates that Abu Burda in the previous chain is named Mughira bin Abu Burda, and Malik named him as such. He was trustworthy, and he was the commander of the military expeditions in Maghrib.