Sahih Bukhari Volume 2, Book 19, Hadith 1180

حَدَّثَنَا عَلِيُّ بْنُ الْجَعْدِ، أَخْبَرَنَا شُعْبَةُ، عَنْ أَنَسِ بْنِ سِيرِينَ، قَالَ سَمِعْتُ أَنَسَ بْنَ مَالِكٍ الأَنْصَارِيَّ، قَالَ قَالَ رَجُلٌ مِنَ الأَنْصَارِ ـ وَكَانَ ضَخْمًا ـ لِلنَّبِيِّ صلى الله عليه وسلم إِنِّي لاَ أَسْتَطِيعُ الصَّلاَةَ مَعَكَ‏.‏ فَصَنَعَ لِلنَّبِيِّ صلى الله عليه وسلم طَعَامًا، فَدَعَاهُ إِلَى بَيْتِهِ، وَنَضَحَ لَهُ طَرَفَ حَصِيرٍ بِمَاءٍ فَصَلَّى عَلَيْهِ رَكْعَتَيْنِ‏.‏ وَقَالَ فُلاَنُ بْنُ فُلاَنِ بْنِ جَارُودٍ لأَنَسٍ ـ رضى الله عنه ـ أَكَانَ النَّبِيُّ صلى الله عليه وسلم يُصَلِّي الضُّحَى فَقَالَ مَا رَأَيْتُهُ صَلَّى غَيْرَ ذَلِكَ الْيَوْمِ‏

Narrated By Anas bin Sirin : I heard Anas bin Malik al-Ansari saying, "An Ansari man, who was very fat, said to the Prophet, 'I am unable to present myself for the prayer with you.' He prepared a meal for the Prophet and invited him to his house. He washed one side of a mat with water and the Prophet offered two Rakat on it." So and so, the son of so and so, the son of Al-Jarud asked Anas, "Did the Prophet use to offer the Duha prayer?" Anas replied, "I never saw him praying (the Duha prayer) except on that day."