The Prophet (may Allah’s peace and blessings be upon him) performed ablution by washing the body parts twice
‘Abdullāh ibn Zayd (may Allah be pleased with him) reported:
The Prophet (may Allah’s peace and blessings be upon him) performed ablution by washing the body parts twice.
أَنَّ النَّبِيَّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ تَوَضَّأَ مَرَّتَيْنِ مَرَّتَيْنِ.
When the Prophet (may Allah's peace and blessings be upon him) performed ablution, he would sometimes wash each body part of the parts of ablution once - washing the face - including rinsing the mouth and sniffing water into the nostrils - and the hands and feet twice.
...:
It is obligatory to wash the body parts of ablution at least once. However, more than once is recommended.
It is permissible to sometimes wash the body parts of ablution twice.
It is prescribed to wipe over the head once.
Sahīh Al-Bukhāri (1/ 43) (158).
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إرشاد الساري لشرح صحيح البخاري (1/ 244).