The last three verses of Psalm 16 show David’s joy and anticipation. He knew that the bond between himself and God could not be broken, not even by death. The covenant between God and David is the basis for his expectation and the cause of his joy.
The way in which David expressed his joy is common in the poetry of his day. Semitic poets often used parallel constructions in which the same thing would be repeated in slightly different ways. In these verses, David uses the words my soul,
my heart,
my flesh,
and your holy one
to refer to himself. The words have different nuances, but all refer to the same person. It has often been thought that the soul would be resurrected while the rest of man did not matter, but David did not make these distinctions. He uses the words heart,
soul,
and flesh
interchangeably.
By this, David did not mean that he would not die, but he did mean that he, as a complete person, would not be left in Sheol forever. He knew that death would not be eternal.
9 Therefore my heart is glad, and my whole being rejoices; my flesh also dwells secure.