Yahya related to me from Malik from Rabia ibn Abi Abd ar-Rahmanthat Muhammad ibn Ibrahim ibn al-Harith at-Taymi said, "I heard myfather say that the aqiqa was desirable, even if it was only asparrow." (RU)
USC-MSA web (English) reference: Book 26, Hadith 5 (RU)
Arabic reference (RU): Book 26, Hadith 1074 (RU)