«وَبِيَدِي زِمَامُهُ، وَظِلِّي إِمَامُهُ»
His leading rein was in my hand, and my shadow went before him.
The narrator guides Abū Zayd as if he cannot see. Zimām ordinarily denotes a leading rein, here applied figuratively to guidance. The elderly woman accompanies them as the third member; the expression “the third hearthstone” heightens the stylized count of three and should be understood in this immediate narrative setting.