A man asked the Messenger of Allah ﷺ: Messenger of Allah, we travel on the sea and take a small quantity of water with us. If we use this for ablution, we would suffer from thirst. Can we perform ablution with sea water? The Messenger ﷺ replied: Its water is pure and what dies in it is lawful food. (Using translation from Abū Dāʾūd 83)  

أَخْبَرَهُ أَنَّهُ سَمِعَ أَبَا هُرَيْرَةَ يَقُولُ سَأَلَ رَجُلٌ النَّبِيَّ ﷺ فَقَالَ إِنَّا نَرْكَبُ الْبَحْرَ وَنَحْمِلُ مَعَنَا الْقَلِيلَ مِنَ الْمَاءِ فَإِنْ تَوَضَّأْنَا بِهِ عَطِشْنَا أَفَنَتَوَضَّأُ مِنْ مَاءِ الْبَحْرِ؟ فَقَالَ رَسُولُ اللَّهِ ﷺ «هُوَ الطَّهُورُ مَاؤُهُ الْحِلُّ مَيْتَتُهُ»  

[Machine] "We were sent the Messenger of Allah ﷺ with three hundred men, and we suffered from hunger until we reached the sea. There, a creature was thrown at us and we ate from it until our bodies were satisfied. Abu Ubaidah took a rib from it and placed it. Then, the longest man in the army carried it on the greatest camel in the army, and it passed under it." This is its meaning.  

«بَعَثَنَا رَسُولُ اللَّهِ ﷺ فِي ثَلَاثِ مِائَةٍ فَأَصَابَنَا جُوعٌ حَتَّى أَتَيْنَا الْبَحْرَ وَقَدْ قَذَفَ دَابَّةً فَأَكَلْنَا مِنْهَا حَتَّى ثَابَتْ أَجْسَامُنَا فَأَخَذَ أَبُو عُبَيْدَةَ ضِلْعًا مِنْ أَضْلَاعِهَا فَوَضَعَهُ ثُمَّ حَمَلَ أَطْوَلَ رَجُلٍ فِي الْجَيْشِ عَلَى أَعْظَمِ بَعِيرٍ فِي الْجَيْشِ فَمَرَّ تَحْتَهُ» هَذَا مَعْنَاهُ