Bulugh al-Maram 120
Narrated Maimuma (rad):
Allah’s Messenger (ﷺ) poured water over his private parts and washed them with his left hand. He then struck his hand against the earth.
وَلَهُمَا فِي حَدِيثِ مَيْمُونَةَ: { ثُمَّ أَفْرَغَ عَلَى فَرْجِهِ, فَغَسَلَهُ بِشِمَالِهِ, ثُمَّ ضَرَبَ بِهَا اَلْأَرْضَ }