Keriah, tearing ones clothes, is one of the most distinctive Jewish mourning practices. It can also seem one of the strangest. As a rabbi, it can be pretty uncomfortable to try to persuade an unprepared and traumatised mourner to rip their clothing at the graveside. As the mourner, it must be far more so.
Keriah comes from the verb meaning to rip or rend. Jewish law requires mourners for close relatives to tear an item of clothing on hearing of the death or at the funeral. For a parent, the tear should be made by the mourner and be plainly visible. For other close relatives, it may be done by someone else and need not show. For parents, a torn garment should be worn the whole shivah.
We read of mourners tearing their clothing in the Bible. Jacob rips his cloak when he hears the (false) report of his son Josephs demise (Genesis 37:34), and David tears his when he receives news of King Sauls death (II Samuel 1:11).
Keriah is a ritualised expression for the anger and grief that a mourner innately feels. In some cultures, the deceaseds property is destroyed; in others, mourners mutilate themselves. Judaism forbids these excessive practices, but recognises and channels the human instincts that provoke them. The halachah of keriah which can appear alien gives vent to a natural impulse. Thus expressing feelings of grief is said to be healing.