It was taught to say when sacrificing: Allahu akbar, la ilaha ill Allahu - God is great, none exists but God. This shows that the sacrifice of our animal self is meant by the law of sacrifice. We should sacrifice our time, our sleep, thinking, "Before my birth I slept and I do not know where I was. In the grave sleep is waiting for me. Now only is the time when I can work." Then the thought comes, "That day I felt as I should not feel, that time I spoke as I should not speak, that year I acted as I should not act. So many months and years, so much of my life is past, and nothing is done that was worthwhile." This makes us think that it is not too late to awaken.