It is narrated from Sayyiduna Imran bin Husayn (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever fights once at sea in the path of Allah - and Allah knows best who is in His path - has rendered to Allah complete obedience to Him, has sought Paradise in every possible way, and has fled from Hell in every possible way."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15427