The Prophet ﷺ sent 300 men under Abu Ubaydah Amir ibn al-Jarrah RA to intercept a Qurayshi caravan, most likely on its way to Syria, but the Quraysh eluded them. As the pursuit continued, supplies ran critically low; Abu Ubaydah collected and rationed all remaining food until it fell to a single date per person per day, and eventually the sahaba resorted to eating khabat, the dried withered leaves of thorn bushes. They reached the shore at Yanbu and found an enormous whale washed ashore. Thirteen or fourteen of the sahaba sat together in the socket of its eye, and Abu Ubaydah rode his largest camel underneath a raised rib bone without lowering his head. The army camped for a month living off the whale and returned to Madinah with the leftover meat. When they asked the Prophet ﷺ whether eating it had been permissible, he asked for a piece and ate from it himself.
Outcome: The army survived near-starvation on the whale; the Prophet ﷺ confirmed seafood as halal by eating from it himself.
A foundational hadith for the ruling, held by all madhhabs except the Hanafi, that all creatures of the sea are lawful to eat without need for slaughter, whether caught or found already dead.
Other events recorded in 6 AH. Their order within the year is not established; use the storyline above for the sequence.
We ran out of food entirely, so we would put the date seeds in our mouths and suck on them, and drink water with them for some taste; we were forced to eat khabat (the dried withered leaves of thorn bushes) just to survive.
We found a massive whale washed ashore at Yanbu, and thirteen or fourteen of us sat together in the socket of its eye. Abu Ubaydah picked out one of its bones, planted it upright on the beach, and rode his largest camel right underneath it without lowering his head.
Do you have any meat of it left? ... Bring it to me.
Asked of the returning sahaba, then he ﷺ ate from the whale meat they had kept, to show it was halal.
Two dead animals are allowed for us: locusts and the whale.
"Sayd al-bahr" (صيد البحر) in the verse refers to what you catch, and "ta'am al-bahr" (طعام البحر) is what is dead and washes up to you.
“It is lawful for you to hunt and eat seafood, as a provision for you and for travelers.”
Cited by the Prophet ﷺ's teaching to explain the permissibility of seafood.