It was narrated that Muhammad bin Hatib said:

"The Messenger of Allah said: 'What differentiates between the lawful and the unlawful is the Duff, and the voice (singing) for the wedding.'"

أَخْبَرَنَا مُجَاهِدُ بْنُ مُوسَى، قَالَ حَدَّثَنَا هُشَيْمٌ، عَنْ أَبِي بَلْجٍ، عَنْ مُحَمَّدِ بْنِ حَاطِبٍ، قَالَ قَالَ رَسُولُ اللَّهِ ﷺ " فَصْلُ مَا بَيْنَ الْحَلاَلِ وَالْحَرَامِ الدُّفُّ وَالصَّوْتُ فِي النِّكَاحِ " .