Musa bin Salamah narrates: Sinan bin Salamah and I went to perform Hajj. When we arrived in Makkah, I said: Come with us to Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both)! We went to him. The narrator says: I asked him about sea water, and he said: Sea water is a means of attaining purification.
Imam Ahmad recorded this narration, and its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1081