When Abraham said: "My Lord, show me how You revive the dead;" He said: "Why, do you not believe?" He said: "Of course [I do], but just to set my heart at ease." He said: "Take four [kinds] of birds and train them to [follow] you; then place a part of them on every mountain. Then call them; they will come to you at once. Know that God is Powerful, Wise."