Developing Humility in Prayer

You should know - may Allah have mercy upon you - that when the slave [of Allah] leaves his house to go to the mosque, that he is going to face Allah, The Irresistible, The One, The Omnipotent, The Exalted in Might, The Oft-forgiving, in the knowledge that nothing is hidden from Allah, wherever it might be, and that nothing is hidden from Allah and that even something as small as a mustard seed is not concealed from Him....