Hadith: Whoever performs ablution as I have done and then stands and prays two Rak‘ahs without letting his thoughts wander, his previous sins will be forgiven

عن حمران مولى عثمان أنَّه رأى عثمان دعا بوَضُوء، فأفرَغ على يَدَيه مِن إنائه، فغَسَلهُما ثلاثَ مرَّات، ثمَّ أدخل يَمينَه في الوَضُوء، ثمَّ تَمضمَض واستَنشَق واستَنثَر، ثُمَّ غَسل وَجهه ثَلاثًا، ويديه إلى المرفقين ثلاثا، ثم مسح برأسه، ثمَّ غَسل كِلتا رجليه ثلاثًا، ثمَّ قال: رأيتُ النَّبِي صلى الله عليه وسلم يتوضَّأ نحو وُضوئي هذا، وقال: (من توضَّأ نحو وُضوئي هذا، ثمَّ صلَّى ركعتين، لا يحدِّث فِيهما نفسه غُفِر له ما تقدَّم من ذنبه).
[صحيح] - [متفق عليه]

Humrān, the freed slave of ‘Uthmān, reported that he saw ‘Uthmān call for water to perform ablution, then he poured the water on his hands from the vessel and washed them three times. Then he put his right hand in the water and rinsed his mouth and his nose. Then he washed his face three times and his arms up to the elbow three times. Then he wiped his head and washed each of his feet three times. Then he said: "I saw the Messenger of Allah (may Allah's peace and blessings be upon him) perform ablution like I have just done." Then he said: "Whoever performs ablution as I have done and then stands and prays two Rak‘ahs without letting his thoughts wander, his previous sins will be forgiven."
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

This great Hadīth comprises the full description of the Prophet's ablution. Out of ‘Uthmān's efficient techniques of teaching, he practically illustrated the Prophet's performance of ablution so that learning would be easier. He asked for a pitcher of water. Once brought to him, he did not put his hands in it in order to avoid spoiling it. Instead, he poured the water on his hands three times until they were cleaned. After that, he put his right hand in the pitcher, took some water, and rinsed his mouth and nose. Then he washed his face three times. Then he washed his hands up to his elbows three times. He then wiped his entire head one time. Then he washed his feet up to his ankles three times. After ‘Uthmān finished this complete ablution, he informed them that he saw the Prophet (may Allah's peace and blessings be upon him) perform a similar ablution. He told them that whoever performs ablution in this way and prays two Rak‘ahs afterwards with humility and without letting his thoughts wander while praying, Allah will grant him great reward for performing this complete ablution and sincere prayer by forgiving his previous sins.