عن عثمان بن عفان رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم:
«مَنْ تَوَضَّأَ فَأَحْسَنَ الْوُضُوءَ خَرَجَتْ خَطَايَاهُ مِنْ جَسَدِهِ حَتَّى تَخْرُجَ مِنْ تَحْتِ أَظْفَارِهِ».  
                        
[صحيح] - [رواه مسلم] - [صحيح مسلم: 245]
                        
 المزيــد ... 
                    
‘Uthmān ibn ‘Affān (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) said:
"Whoever performs ablution perfectly, his sins will come out from his body, to the extent that it will come out from under his nails." 
                                                     
                                                                                                    
[Authentic hadith] - [Narrated by Muslim] - [Sahih Muslim - 245]                                            
The Prophet (may Allah's peace and blessings be upon him) informs that if a person performs ablution while observing its Sunnahs and etiquettes, this will cause his sins and misdeeds to be expiated and forgiven - to the extent that his sins will come out from under the nails of his hands and feet.