It was narrated that ‘Ali bin Abu Talib said that when he washed the Messenger of Allah ﷺ he looked for what which is usually looked for on the deceased (i.e., dirt), and he found none. He said:
“May my father be sacrificed for you, you are pure; you were pure in life and you are pure in death.”

حَدَّثَنَا يَحْيَى بْنُ خِذَامٍ، حَدَّثَنَا صَفْوَانُ بْنُ عِيسَى، أَنْبَأَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ، قَالَ لَمَّا غَسَّلَ النَّبِيَّ ـ ﷺ ـ ذَهَبَ يَلْتَمِسُ مِنْهُ مَا يَلْتَمِسُ مِنَ الْمَيِّتِ فَلَمْ يَجِدْهُ . فَقَالَ بِأَبِي الطَّيِّبُ طِبْتَ حَيًّا وَطِبْتَ مَيِّتًا .