Muhammad, the Prophet of Islam who passed away in 632, related:
“Gabriel came to me and said, ‘O Muhammad, live as you wish, for you shall eventually die. Love whom you desire, for you shall eventually depart. Do what you please, for you shall pay. Know that the night-prayer  is the honor of a believer, and his pride is being independent on others.’” [Silsilah al-Saheehah]
»أتاني جبريل، فقال: يا محمد! عش ما شئت فإنك ميت، وأحبب من شئت فإنك مفارقه، واعمل ماشئت فإنك مجزي به، و اعلم أن شرف المؤمن قيامه بالليل، و عزه استغناؤه عن الناس«السلسلة الصحيحة
If there is only one thing certain about life, it is that it ends. This truism instinctively raises a question which preoccupies most people at least once in their life: What lies beyond death?
At the physiological level, the journey that the deceased takes is plain for all to witness. If left alone to natural causes,  the heart will stop beating, the lungs will stop breathing, and the body’s cells will be starved of blood and oxygen. The termination of blood flow to the outer extremities will soon turn them pale. With the oxygen cut off, cells will respire anaerobically for a time, producing the lactic acid which causes rigor mortis – the stiffening of the corpse’s muscles. Then, as the cells begin to decompose, the stiffness wanes, the tongue protrudes, the temperature drops, the skin discolors, the flesh rots, and the parasites have their feast – until all that is left is dried-out tooth and bone.
As for the journey of the soul after death, then this is not something that can be witnessed, nor can it be gauged through scientific enquiry. Even in a living body, the conscious, or soul, of a person cannot be subjected to empirical experimentation. It is simply beyond human control. In this regard, the concept of a Hereafter – a life beyond death, resurrection, and a Day of Reckoning; not to mention the existence of a Divine, Omnipotent Creator, His angels, destiny, and so on – comes under the subject of belief in the unseen. The only way in which man can come to know anything of the unseen world is through divine revelation.