Sahih al-Bukhari — Virtues of the Qur'an — Hadith No: 5018
Translation
Narrated Usaid bin Hudair: That while he was reciting Surat Al-Baqara (The Cow) at night, and his horse was tied beside him, the horse was suddenly startled and troubled. When he stopped reciting, the horse became quiet, and when he started again, the horse was startled again. Then he stopped reciting and the horse became quiet too. He started reciting again and the horse was startled and troubled once again. Then he stopped reciting and his son, Yahya was beside the horse. He was afraid that the horse might trample on him. When he took the boy away and looked towards the sky, he could not see it. The next morning he informed the Prophet who said, "Recite, O Ibn Hudair! Recite, O Ibn Hudair!" Ibn Hudair replied, "O Allah's Messenger (ﷺ)! My son, Yahya was near the horse and I was afraid that it might trample on him, so I looked towards the sky, and went to him. When I looked at the sky, I saw something like a cloud containing what looked like lamps, so I went out in order not to see it." The Prophet (ﷺ) said, "Do you know what that was?" Ibn Hudair replied, "No." The Prophet (ﷺ) said, "Those were Angels who came near to you for your voice and if you had kept on reciting till dawn, it would have remained there till morning when people would have seen it as it would not have disappeared