The Prophet (peace be upon him and his family): And know that this thin skin has no endurance against the Fire, so have mercy on yourselves, for you have tested yourselves in the tribulations of the world [and have not been able to bear even its smallest setbacks]. Have you not seen how one of you groans and cries out in pain from a thorn that pierces his body, from a stumble that draws his blood, and from hot sand that burns him? So what will his state be when he is between two slabs of fire, sharing a bed with burning stone and a companion of Satan? … Do you know that when Malik, [the keeper] of Hell, becomes angry with the Fire, out of his anger the Fire [seethes and rages and] its parts crush one another (piling one upon another), and when he rebukes it (shouts at it), losing all patience it leaps up moaning between the gates of Hell out of his rebuke? O aged elder whom the frailty of old age has overtaken, how will you be when the collars of Fire cling to the bones of the necks and the fetters and chains cling until they devour the flesh of the arms? So, O company of servants, fear Allah! Fear Allah while you are in good health before illness [and the arrival of death], and in ease and comfort [of the world] before the narrowness and hardship [of the grave] you are at rest (you are able to obtain the pleasure of Allah and His Messenger (peace be upon him and his family) and to be delivered from the calamity that follows death). So strive to free your necks before those necks are pawned. Keep your eyes awake (spend the nights in worship) and make your bellies lean (fast), and put your feet to work (step forward in good deeds), and spend your wealth [in the way of Allah], and sacrifice your bodies for your souls, and do not be miserly in this matter (use these bodies — which will soon perish and rot beneath the dust — in worship, servitude and jihad against the enemies of the faith, so that you may be delivered from everlasting punishment and dwell in the eternal Paradise), for Allah the Glorified has said: إِنْ تَنْصُرُوا اللهَ یَنْصُرْکُمْ وَ یُثَبِّتْ أَقْدامَکُمْ [If you help (the cause of) Allah, He will help you and make firm your feet].