Sunan Ibn Majah 386
It was narrated that Mughirah bin Abu Burdah, who was from the tribe of Banu 'Abdud-Dar, said that:
He heard Abu Hurairah say: "A man came to the Messenger of Allah and said: "O Messenger of Allah, we travel by sea and carry a small amount of water with us. If we use it for ablution, we will become thirsty. Can we perform ablution with seawater?' The Messenger of Allah said: 'Its water is a means of purification, ad its dead meat is permissible. (i.e. the fish found dead in the sea).'"
حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا مَالِكُ بْنُ أَنَسٍ، حَدَّثَنِي صَفْوَانُ بْنُ سُلَيْمٍ، عَنْ سَعِيدِ بْنِ سَلَمَةَ، - هُوَ مِنْ آلِ ابْنِ الأَزْرَقِ - أَنَّ الْمُغِيرَةَ بْنَ أَبِي بُرْدَةَ، - وَهُوَ مِنْ بَنِي عَبْدِ الدَّارِ - حَدَّثَهُ أَنَّهُ، سَمِعَ أَبَا هُرَيْرَةَ، يَقُولُ جَاءَ رَجُلٌ إِلَى رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ فَقَالَ يَا رَسُولَ اللَّهِ إِنَّا نَرْكَبُ الْبَحْرَ وَنَحْمِلُ مَعَنَا الْقَلِيلَ مِنَ الْمَاءِ فَإِنْ تَوَضَّأْنَا بِهِ عَطِشْنَا أَفَنَتَوَضَّأُ مِنْ مَاءِ الْبَحْرِ فَقَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏
"‏ هُوَ الطَّهُورُ مَاؤُهُ الْحِلُّ مَيْتَتُهُ ‏"‏ ‏.‏