https://abukhadeejah.com/seeking-blessings-from-the-wudu-water-sweat-hair-blood-and-traces-of-the-prophet-and-the-pious/
Seeking Blessings from the Wudū-Water, Sweat, Hair, Blood and Traces of the Prophet (peace and blessings be upon him) and the Sharī'ah Prohibition on Seeking Blessings from the Traces and Leftovers of the Scholars and Pious Ones. (Shaikh Ibn Bāz)