I say, and with God's success: The skin of a human cannot be purified by tanning; due to the honor of a human being. Refer to: Sharh Al-Wiqayah p. 100-101, Fath Al-Qadeer 1: 18, Al-Hidayah 1: 20, Al-Badai 1: 63, Al-Mukhtar 1: 24, Al-Kanz p. 8, and God knows best.