"And indeed, I fear the Mawali (kinsmen) after me," meaning: the agnates (asaba) who would inherit from me. "After me" means after my death. He wanted someone from his own loins to inherit his wealth. In the exegesis of Qatada: "And my wife has been barren," meaning: she has not given birth. "So give me from Yourself"—meaning from Your presence—"an heir," meaning a son.