IABOC (Heb. Jabbāq). — Eastern tributary of the Jordan. It is famous in the Bible for the nocturnal struggle sustained on its banks (v. PHANUEL) Jacob (v.), returning from Mesopotamia, with a mysterious personage (Jahweh or the angel of Jahweh?), who changed his name to «Israel» (Gen. 32, 23-30; 33, 17-20). Mahanaim (v.) and divided Gilead into two equal parts (Ios. 12, 2; Iudc. 11, 13-22). It marked the boundary between the Kingdom of Og (Bashan) and that of Sehon (Hesebon), as well as the northern frontier of the Ammonites (Num. 21, 24; Deut. 2, 37; 3, 16. Cf. Fl. Giuseppe, Antiq. Iud., IV, 5, 2, 3). It also occurs in Iudt. 2, 24 (according to the Pēlīṭā).
Many itineraries placed it approximately 3 km. south of Lake Hūleh, on account of the so-called «Jacob’s bridge»; others placed it 2 or 3 miles south of Lake Tiberias; still others confused it with the Jarmūk. Today it is commonly identified with the Nahr ez-Zerqā («blue river»), the most important of the Jordan’s tributaries after the Jarmūk. It begins at the 'Ammān stream (788 m. above sea level), west of the city of the same name, but its actual source (Rās ez-Zerqā) is near the Qal'at ez-Zerqā, where it receives the waters of the 'Ajn ez-Zerqā', and then, describing a great arc 70 km. long, flows into the Jordan near the bridge of ed-Damjeh, opposite Qarn Sarqabah. On average it is 7 m. wide and 60 cm. deep. The water is clear and rich in fish; the bed is deeply entrenched; the banks are steep, yet extraordinarily picturesque on account of the broom, oleanders, etc. Its tributaries are the rivers Wādi ed-Dlejl, el-Qnejjeh, er-Rijāšī, the Sejl Gerāš, etc.