The most striking Jewish expression of grief is the rending of garments (Kria or Keriah) by the mourner prior to the funeral service.
The Bible records many instances of rending the clothes after the news of death. When Jacob saw Joseph's coat of many colors drenched with what he thought to be his son's blood, he rent his garments. Likewise, David tore his clothes when he heard of the death of King Saul, and Job, who knew grief so well, stood up and rent his mantle.
This act of mourning extends not just to relatives but to revered teachers and also to seeing the ruins of Jerusalem for the first time in at least a month.