His grandfather embraced Islam during the time of the Prophet ﷺ, who instructed him to perform a ritual bath with water and lote leaves.
حدثنا وكيع حدثنا سفيان عن الأغر المنقري
أن جده أسلم على عهد النبي ﷺ فأمره أن يغتسل بماء وسدر
Its chain of transmission is sahih, mentioned previously in 20489.