As for the prayer, its significance ---- or rather part of its significance --- is that it empties the heart from bad feelings and fills it with strength and pleasure. During prayer, one's heart and soul are in communication with Allah. Closeness to Him, the comfort realized from asking of Him, and the spirituality felt from standing in front of Him---- these are all realized during the prayer. Every limb is used in the prayer, but what is more important is that the heart must be wakeful as well. When one prays, tranquility and peace are achieved, as one travels away, at least spiritually, from enemies and troubles.
Thus the prayer is one of the most potent of remedies for the diseases of the heart. Yet only the worthy heart benefits from prayer; the weak heart, on the other hand, is like the body, in that it seeks its sustenance from material matter.
Therefore prayer is the greatest way to help us achieve the blessings of both this world and the Hereafter. The prayer precludes one from sins, defends against diseases, illuminates both heart and face, makes one active, and in general, brings good upon the person who performs it sincerely.