By this name, unaccompanied by patronymic or cognomen, are known four amoraim, three of whom were members of the family of Abba Arika (Rab) in Babylonia, and the remaining one was a distinguished Palestinian. 1. The father of Rab, and elder half-brother of Ḥiyya the Great, a lineal or lateral descendant of the royal house of David (Ket. 62b; Yer Ta'anit, iv. 68a; Gen. R. xcviii.). After the birth of Aibu, his father, having become a widower, married a widow who had a daughter, and from that union came Ḥiyya. Aibu married his step-sister, and was thus related to Ḥiyya as both half-brother and brother-in-law (Sanh. 5a, Pes. 4a). Aibu was a disciple of Eleazar b. Zadok (Suk. 44b); and Ḥiyya, speaking to Rab, often addressed him as Bar Paḥate (Son of Nobles; Ber. 13b), thus testifying to the noble gifts of his elder half-brother. 2. A son of Rab, who inherited his name from his grandfather, but not his scholarly capacity. His father, seeing that Aibu was not endowed with great mental gifts, advised him to turn his attention to secular pursuits, and furnished him with a number of practical rules of conduct. Aibu became a farmer; and some had occasion to criticize him for not observing a rabbinical enactment (Pes. 113a; B. M. 93b; 'Ab. Zarah, 35b). 3. A grandson of Rab (Suk. 44b). So little was he known as an authority on the Halakah, that the name of his Palestinian contemporary Abbahu was sometimes substituted for his (Pes. 46a, Ḥul. 122b et seq.). 4. See following article.