It was stated: Rabbi Yosei, son of Rabbi Ḥanina, said: The practice of praying three times daily is ancient, albeit not in its present form; prayers were instituted by the Patriarchs. However, Rabbi Yehoshua ben Levi said that the prayers were instituted based on the daily offerings sacrificed in the Holy Temple, and the prayers parallel the offerings, in terms of both time and characteristics.
Prayer is in place of sacrifices (korbanot), and therefore one must be careful to follow the format of sacrifices with respect to intention, and not let other thoughts mix in, similar to unrelated thoughts which would nullify sacrifices. And prayer must be recited standing, like the service in the temple; and in a fixed place like the sacrifices, where each one had a fixed place for its slaughter and the sprinkling of its blood; and that nothing should separate between one and the wall [during prayer], similar to sacrifices where any separation between it and the vessel would nullify it; and it is appropriate that one should have special nice garments for prayer, like the clothing of the kohahim, though understandably not everyone can spend the money on this; and in any case it is appropriate to have special pants for prayer, for the sake of cleanliness.