Complex sentence: Abdullah ibn Ziyad explained to him that while he was half-awake or half-asleep, a man appeared before him in his dream and told him that the human voice ought to be used to call the Muslims to prayer.
Split into simpler sentences: Abdullah ibn Ziyad explained to him that while he was half-awake or half-asleep, a man appeared before him in his dream. And told Abdullah that the human voice ought to be used to call the Muslims to prayer.