Muwatta Imam Malik Book of Purity, Hadith 6

Yahya related to me from Malik from Yahya ibn Muhammad ibn Talha from Uthman ibn Abd ar-Rahman that his father related to him that he had heard that Umar ibn al-Khattab used to wash what was beneath his waist wrapper with water.

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ مُحَمَّدِ بْنِ طَحْلاَءَ، عَنْ عُثْمَانَ بْنِ عَبْدِ الرَّحْمَنِ، أَنَّ أَبَاهُ، حَدَّثَهُ أَنَّهُ، سَمِعَ عُمَرَ بْنَ الْخَطَّابِ، يَتَوَضَّأُ بِالْمَاءِ لِمَا تَحْتَ إِزَارِهِ .