In Jewish custom at that time, people were usually buried on the same day they died. Families placed the body in a tomb quickly, often within hours.
John tells us that Lazarus had been in the tomb for four days. This detail is important. It shows that Lazarus was truly dead.
Because four days had passed, this miracle was not a simple resuscitation (bringing someone back who only seemed dead). Jesus did not restore a weak person who might recover. He raised a man who had been dead and buried for several days.