مُوَطَّأُ مَالِكٍ
Muwatta Malik 428
Shortening the Prayer
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عُمَرَ بْنَ الْخَطَّابِ، بَنَى رَحْبَةً فِي نَاحِيَةِ الْمَسْجِدِ تُسَمَّى الْبُطَيْحَاءَ وَقَالَ مَنْ كَانَ يُرِيدُ أَنْ يَلْغَطَ أَوْ يُنْشِدَ شِعْرًا أَوْ يَرْفَعَ صَوْتَهُ فَلْيَخْرُجْ إِلَى هَذِهِ الرَّحْبَةِ .
Yahya related to me from Malik that he had heard that Umar ibn al-Khattab set aside an area near the mosque called al-Butayha and said, "Whoever wishes to talk nonsense or recite poetry or raise his voice should go to that area."
Arabic/English book reference: Book 9, Hadith 96