Quran 18:61 · Al-Kahf

God continuously manages the affairs of this world through His angels. Since this system is not visible to man, he does not fully grasp its secrets. He harbours different types of doubts due to his deficient knowledge. To remedy this, God has given the opportunity for indirect observation to certain of His selected subjects. He has arranged for them to observe His invisible world, so that they should see with their own eyes its wisdom and make others aware of it. Here, the incident relating to Moses is a similar type of exceptional event, by means of which he was given a glimpse of God’s invisible system. Moses is said to have undertaken this journey between Egypt and Sudan along with one young disciple Yusha‘ bin Nun (Joshua). By way of a sign, God had asked him to proceed on his journey until he reached a place where two seas came together. He was told that there he would find somebody (perhaps an angel in the shape of a human being), whom he was asked to accompany.