صحيح البخاري Sahih Bukhari كتاب الجمعة The Book of Al-Jumuah (Friday)
بَابُ الْجُلُوسِ عَلَى الْمِنْبَرِ عِنْدَ التَّأْذِينِ:

(24) Chapter. To sit on the pulpit while Adhan is being pronounced.

1 hadith
Hadith 915
حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ ، قَالَ : حَدَّثَنَا اللَّيْثُ ، عَنْ عُقَيْلٍ ، عَنِ ابْنِ شِهَابٍ ، أَنَّ السَّائِبَ بْنَ يَزِيدَ أَخْبَرَهُ ، " أَنَّ التَّأْذِينَ الثَّانِيَ يَوْمَ الْجُمُعَةِ أَمَرَ بِهِ عُثْمَانُ حِينَ كَثُرَ أَهْلُ الْمَسْجِدِ ، وَكَانَ التَّأْذِينُ يَوْمَ الْجُمُعَةِ حِينَ يَجْلِسُ الْإِمَامُ " .
Narrated As-Sa'ib bin Yazid I: `Uthman bin `Affan introduced the second Adhan on Fridays when the number of the people in the mosque increased. Previously the Adhan on Fridays used to be pronounced only after the Imam had taken his seat (on the pulpit).
Hadith Reference Sahih Bukhari / The Book of Al-Jumuah (Friday) / Hadith: 915
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة