The Messenger of Allah ﷺ said, "What distinguishes the lawful from the unlawful in marriage is the beating of the duff and the raising of voices in song."
أخبرنا مجاهد بن موسى قال حدثنا هشيم عن أبي بلج
قال رسول الله ﷺ فصل ما بين الحلال والحرام الدف والصوت في النكاح
[Hasan] Reported by Tirmidhi, in the Book of Marriage, Chapter on What Has Been Said About Announcing Marriage, Hadith: 1088, from the hadith of Hushaym, with the same chain, and he explicitly stated hearing it, and Tirmidhi said, hasan. The hadith is also in al-Kubra, Hadith: 5562, and Hakim graded it sahih: 2/184, and Dhahabi agreed with him.Abu Balj is Yahya bin Abu Salim, and Muhammad bin Hatib is al-Jumahi.