David could certainly say this because he was confronted with great danger at all times. Many times the Psalmist had made a narrow escapes in preserving his life. If Jesus tarries his coming many more years, many of us here today will be faced with our own physical death. Most appointments you can cancel, but this one no man can council. Death is merely the separation of the soul and spirit from the body.
Man is a tri-part being.
As there is a Father, Son and Holy Ghost in the God head, man has a trinity, which is body, soul and spirit. When a Christian dies he goes to the blissful place called heaven. On the other hand, when a lost sinner dies, he goes to a dreadful, awful, torturous place called hell. In the Bible there are mainly three kinds of death which are emphacises. Secondly, there is eternal death , which is separation from Holy God forever and ever.