Abdullah bin Umar (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) said: "Two bloods and two dead things have been made lawful for us. The two bloods are the liver and the spleen, and the two dead things are fish and locusts."
Abd al-Rahman and his two brothers narrated it in this way from their father, while others narrated it as mawquf (a statement of Ibn Umar), and that is the correct version.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19697