(72) باب إِعْلاَنِ النِّكَاحِ بِالصَّوْتِ وَضَرْبِ الدُّفِّ .
It was narrated that Abu Balj said:
"I heard Muhammad bin Hatib say: 'What differentiates between the lawful and the unlawful is the voice (singing).'" (FR)
Reference (FR): Sunan an-Nasa'i 3370 (FR)
In-book reference (FR): Book 26, Hadith 175 (FR)
English translation (FR): Vol. 4, Book 26, Hadith 3372 (FR)