How sound is the story of Al-Hayban, the Jewish rabbi, emigrating to Medina to await the Arab prophet mentioned in the Torah, as narrated in the biography of the Companion Zayd ibn Sa'nah?

The People of the Book knew the description of the awaited Prophet and his migration to Medina. Many of their rabbis had migrated from Ash-Sham to Medina before the Prophethood, anticipating his appearance. Among them was Ibn al-Hayyaban, who came from Ash-Sham to Medina two years before the Prophet's mission. He informed the Jews that he had come expecting the emergence of a prophet whose migration would be to these lands, and he advised them to follow him, warning against disobeying him. When Qurayza was conquered, three young men among them remembered Ibn al-Hayyaban's وصية (will/bequest) and embraced Islam. There was also a Syrian monk named Aysu in Mecca who informed its people of the imminent birth of a prophet who would rule the Arabs and non-Arabs, and that he had come to Mecca seeking this prophet.