صحيح البخاري
Sahih Bukhari
كتاب الأذان
The Book of Adhan
بَابُ إِذَا أُقِيمَتِ الصَّلاَةُ فَلاَ صَلاَةَ إِلاَّ الْمَكْتُوبَةَ:
(38) Chapter. No Salat (prayer) (is to be offered) except the compulsory Salat after the Iqama has been pronounced for that compulsory Salat.
1 hadith
Hadith 663
Narrated Malik Ibn Buhaina: Allah's Apostle passed by a man praying two rak`at after the Iqama (had been pronounced). When Allah's Apostle completed the prayer, the people gathered around him (the Prophet) or that man and Allah's Apostle said to him (protesting), Are there four rak`at in Fajr prayer? Are there four rak`at in Fajr prayer?"