It was narrated that ‘Abdullah bin Harith said: “During the caliphate of ‘Uthman, when the people were present in large numbers, I asked about Duha prayer, and I could not find anyone who could tell me that he, meaning the Prophet (ﷺ), had prayed it, apart from Umm Hani’. She told me that he had prayed it with eight Rak’ah.”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ يَزِيدَ بْنِ أَبِي زِيَادٍ، عَنْ عَبْدِ اللَّهِ بْنِ الْحَارِثِ، قَالَ سَأَلْتُ فِي زَمَنِ عُثْمَانَ بْنِ عَفَّانَ وَالنَّاسُ مُتَوَافِرُونَ - أَوْ مُتَوَافُونَ - عَنْ صَلاَةِ الضُّحَى، فَلَمْ أَجِدْ أَحَدًا يُخْبِرُنِي أَنَّهُ صَلاَّهَا - يَعْنِي النَّبِيَّ ـ صلى الله عليه وسلم ـ - غَيْرَ أُمِّ هَانِئٍ فَأَخْبَرَتْنِي أَنَّهُ صَلاَّهَا ثَمَانِيَ رَكَعَاتٍ .
sunnah.com