Hiraṇyakaśipu was very much afraid of Viṣṇu’s becoming an animal to kill him because his brother had been killed by Viṣṇu when the Lord took the shape of a boar. He was therefore very careful to guard against all kinds of animals. But even without taking the shape of an animal, Viṣṇu could kill him by hurling His Sudarśana cakra, which can go anywhere without the Lord’s physical presence. Therefore Hiraṇyakaśipu was careful to guard against all kinds of weapons. He guarded against all kinds of time, space and countries because he was afraid of being killed by someone else in another land. There are many other planets, higher and lower, and therefore he prayed for the benediction of not being killed by any resident of any of these planets. There are three original deities — Brahmā, Viṣṇu and Maheśvara. Hiraṇyakaśipu knew that Brahmā would not kill him, but he also wanted not to be killed by Lord Viṣṇu or Lord Śiva. Consequently, he prayed for such a benediction. Thus Hiraṇyakaśipu thought himself securely protected from any kind of death caused by any living entity within this universe. He also carefully guarded against natural death, which might take place within his house or outside of the house.