The explanation that Chazal give on the verse “Yisrael, prepare yourself to meet your G-d!” is well-known. They say that when a person I praying or learning he must ensure that he is dressed smartly, as the Divine Presence is with him. Even when sitting at home privately, he must behave as if standing before the rulers of the town. The exact details depend on the custom in that place. Many people do not keep this law when praying at home in the evening or getting up early to learn, and they must be very careful to keep it.