Sayyiduna Abdullah bin Umar (may Allah be pleased with him) says: "Two kinds of blood and two kinds of dead animals have been made lawful for us: the locust and the fish, the liver and the spleen." (b) This hadith is sahih (authentic) and has the ruling of a marfu' report (from the Prophet). The sons of Zayd narrated it from their father as marfu'.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1196