Ibn Jurayj (may Allah have mercy on him) narrates from Ibn Shihab al-Zuhri (may Allah have mercy on him) concerning the saying of Allah Almighty: "He increases in creation whatever He wills" [Surah Fatir: 1], that what is meant by it is a beautiful voice.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 21056