17 Or “my life.” The suffixed form of נֶפֶשׁ (nefesh, “being”) is often equivalent to a pronoun in poetic texts.
18 In ancient Israelite cosmology Sheol is the realm of the dead, viewed as being under the earth’s surface. See L. I. J. Stadelmann, The Hebrew Conception of the World, 165–76.
19 A “faithful follower” (חָסִיד [khasid], traditionally rendered “holy one”) is one who does what is right in God’s eyes and remains faithful to God (see Pss 4:3; 12:1; 18:25; 31:23; 37:28; 86:2; 97:10). The psalmist here refers to himself, as the parallel line (“You will not abandon me to Sheol”) indicates.
20 That is, “experience.” The psalmist is confident that the Lord will protect him in his present crisis (see v. 1) and prevent him from dying. According to Peter, the words of Ps 16:8–11 are applicable to Jesus (Acts 2:25–29). Peter goes on to argue that David, being a prophet, foresaw future events and spoke of Jesus’ resurrection from the dead (Acts 2:30–33). Paul seems to concur with Peter in this understanding (see Acts 13:35–37). For a discussion of the NT application of these verses to Jesus’ resurrection, see R. B. Chisholm, Jr., “A Theology of the Psalms,” A Biblical Theology of the Old Testament, 292–95.
21 The Hebrew word שָׁחַת (shakhat, “pit”) is often used as a title for Sheol (see Pss 30:9; 49:9; 55:24; 103:4). Note the parallelism with the previous line.