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كتاب الأذان
10  
Call to Prayers (Adhaan)
(41)
Chapter: Can the Imam offer the Salat (prayer) with only those who are present (for the prayer)? And can be deliver a Khutba (religious talk) on Friday if it is raining?
(41)
باب هَلْ يُصَلِّي الإِمَامُ بِمَنْ حَضَرَ وَهَلْ يَخْطُبُ يَوْمَ الْجُمُعَةِ فِي الْمَطَرِ
Sahih al-Bukhari 670

Narrated Anas bin Seereen:

I heard Anas saying, "A man from Ansar said to the Prophet, 'I cannot pray with you (in congregation).' He was a very fat man and he prepared a meal for the Prophet (ﷺ) and invited him to his house. He spread out a mat for the Prophet, and washed one of its sides with water, and the Prophet (ﷺ) prayed two rak`at on it." A man from the family of Al-Jaruid [??] asked, "Did the Prophet (ﷺ) used to pray the Duha (forenoon) prayer?" Anas said, "I did not see him praying the Duha prayer except on that day."

حَدَّثَنَا آدَمُ، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ حَدَّثَنَا أَنَسُ بْنُ سِيرِينَ، قَالَ سَمِعْتُ أَنَسًا، يَقُولُ قَالَ رَجُلٌ مِنَ الأَنْصَارِ إِنِّي لاَ أَسْتَطِيعُ الصَّلاَةَ مَعَكَ‏.‏ وَكَانَ رَجُلاً ضَخْمًا، فَصَنَعَ لِلنَّبِيِّ صلى الله عليه وسلم طَعَامًا فَدَعَاهُ إِلَى مَنْزِلِهِ، فَبَسَطَ لَهُ حَصِيرًا وَنَضَحَ طَرَفَ الْحَصِيرِ، صَلَّى عَلَيْهِ رَكْعَتَيْنِ‏.‏ فَقَالَ رَجُلٌ مِنْ آلِ الْجَارُودِ لأَنَسٍ أَكَانَ النَّبِيُّ صلى الله عليه وسلم يُصَلِّي الضُّحَى قَالَ مَا رَأَيْتُهُ صَلاَّهَا إِلاَّ يَوْمَئِذٍ‏.‏
Reference : Sahih al-Bukhari 670
In-book reference : Book 10, Hadith 64
USC-MSA web (English) reference : Vol. 1, Book 11, Hadith 639
  (deprecated numbering scheme)