Sahih al-Bukhari · Hadith 5190

Wedlock, Marriage (Nikaah)

Narrated 'Urwa: Aisha said, "While the Ethiopians were playing with their small spears, Allah's Messenger (ﷺ) screened me behind him and I watched (that display) and kept on watching till I left on my own." So you may estimate of what age a little girl may listen to amusement