A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
psa 16:1Michtam, or, by the change of one letter, Michtab--a "writing," such as a poem or song (compare Isa 38:9). Such a change of the letter m for b was not unusual. The position of this word in connection with the author's name, being that usually occupied by some term, such as Psalm or song, denoting the style or matter of the composition, favors this view of its meaning, though we know not why this and Psalms 56-60 should be specially, called "a writing." "A golden (Psalm)," or "a memorial" are explanations proposed by some--neither of which, however applicable here, appears adapted to the other Psalms where the term occurs. According to Peter (Act 2:25) and Paul (Act 13:35), this Psalm relates to Christ and expresses the feelings of His human nature, in view of His sufferings and victory over death and the grave, including His subsequent exaltation at the right hand of God. Such was the exposition of the best earlier Christian interpreters. Some moderns have held that the Psalm relates exclusively to David; but this view is expressly contradicted by the apostles; others hold that the language of the Psalm is applicable to David as a type of Christ, capable of the higher sense assigned it in the New Testament. But then the language of Psa 16:10 cannot be used of David in any sense, for "he saw corruption." Others again propose to refer the first part to David, and the last to Christ; but it is evident that no change in the subject of the Psalm is indicated. Indeed, the person who appeals to God for help is evidently the same who rejoices in having found it. In referring the whole Psalm to Christ, it is, however, by no means denied that much of its language is expressive of the feelings of His people, so far as in their humble measure they have the feelings of trust in God expressed by Him, their head and representative. Such use of His language, as recorded in His last prayer (John 17:1-26), and even that which He used in Gethsemane, under similar modifications, is equally proper. The propriety of this reference of the Psalm to Christ will appear in the scope and interpretation. In view of the sufferings before Him, the Saviour, with that instinctive dread of death manifested in Gethsemane, calls on God to "preserve" Him; He avows His delight in holiness and abhorrence of the wicked and their wickedness; and for "the joy that was set before Him, despising the shame" [Heb 12:2], encourages Himself; contemplating the glories of the heritage appointed Him. Thus even death and the grave lose their terrors in the assurance of the victory to be attained and "the glory that should follow" [Pe1 1:11]. (Psa 16:1-11)
Preserve me, &c.--keep or watch over my interests.
in thee . . . I . . . trust--as one seeking shelter from pressing danger.
psa 16:2my soul--must be supplied; expressed in similar cases (Psa 42:5, Psa 42:11).
my goodness . . . thee--This obscure passage is variously expounded. Either one of two expositions falls in with the context. "My goodness" or merit is not on account of Thee--that is, is not for Thy benefit. Then follows the contrast of Psa 16:3 (but is), in respect, or for the saints, &c.--that is, it enures to them. Or, my goodness--or happiness is not besides Thee--that is, without Thee I have no other source of happiness. Then, "to the saints," &c., means that the same privilege of deriving happiness from God only is theirs. The first is the most consonant with the Messianic character of the Psalm, though the latter is not inconsistent with it.
psa 16:3saints--or, persons consecrated to God, set apart from others to His service.
in the earth--that is, land of Palestine, the residence of God's chosen people--figuratively for the Church.
excellent--or, "nobles," distinguished for moral excellence.
psa 16:4He expresses his abhorrence of those who seek other sources of happiness or objects of worship, and, by characterizing their rites by drink offerings of blood, clearly denotes idolaters. The word for "sorrows" is by some rendered "idols"; but, though a similar word to that for idols, it is not the same. In selecting such a term, there may be an allusion, by the author, to the sorrows produced by idolatrous practices.
psa 16:5God is the chief good, and supplies all need (Deu 10:9).
portion of mine inheritance and of my cup--may contain an allusion to the daily supply of food, and also to the inheritance of Levi (Deu 18:1-2).
maintainest--or, drawest out my lot--enlargest it. Psa 16:7 carries out this idea more fully.
psa 16:7given me counsel--cared for me.
my reins--the supposed seat of emotion and thought (Psa 7:9; Psa 26:2).
instruct me--or, excite to acts of praise (Isa 53:11-12; Heb 12:2).
psa 16:8With God's presence and aid he is sure of safety (Psa 10:6; Psa 15:5; Joh 12:27-28; Heb 5:7-8).
psa 16:9glory--as heart (Psa 7:5), for self. In Act 2:26, after the Septuagint, "my tongue" as "the glory of the frame"--the instrument for praising God.
flesh--If taken as opposed to soul (Psa 16:10), it may mean the body; otherwise, the whole person (compare Psa 63:1; Psa 84:2).
rest in hope--(compare Margin).
psa 16:10soul--or, "self." This use of "soul" for the person is frequent (Gen 12:5; Gen 46:26; Psa 3:2; Psa 7:2; Psa 11:1), even when the body may be the part chiefly affected, as in Psa 35:13; Psa 105:18. Some cases are cited, as Lev 22:4; Num 6:6; Num 9:6, Num 9:10; Num 19:13; Hag 2:13, &c., which seem to justify assigning the meaning of body, or dead body; but it will be found that the latter sense is given by some adjunct expressed or implied. In those cases person is the proper sense.
wilt not leave . . . hell--abandon to the power of (Job 39:14; Psa 49:10). Hell as (Gen 42:38; Psa 6:5; Jon 2:2) the state or region of death, and so frequently--or the grave itself (Job 14:13; Job 17:13; Ecc 9:10, &c.). So the Greek Hades (compare Act 2:27, Act 2:31). The context alone can settle whether the state mentioned is one of suffering and place of the damned (compare Psa 9:17; Pro 5:5; Pro 7:27).
wilt . . . suffer--literally, "give" or "appoint."
Holy One-- (Psa 4:3), one who is the object of God's favor, and so a recipient of divine grace which he exhibits--pious.
to see--or, "experience"--undergo (Luk 2:26).
corruption--Some render the word, the pit, which is possible, but for the obvious sense which the apostle's exposition (Act 2:27; Act 13:36-37) gives. The sense of the whole passage is clearly this: by the use of flesh and soul, the disembodied state produced by death is indicated; but, on the other hand, no more than the state of death is intended; for the last clause of Psa 16:10 is strictly parallel with the first, and Holy One corresponds to soul, and corruption to hell. As Holy One, or David (Act 13:36-37), which denotes the person, including soul and body, is used for body, of which only corruption can be predicated (compare Act 2:31); so, on the contrary, soul, which literally means the immaterial part, is used for the person. The language may be thus paraphrased, "In death I shall hope for resurrection; for I shall not be left under its dominion and within its bounds, or be subject to the corruption which ordinarily ensues."
psa 16:11Raised from the dead, he shall die no more; death hath no more dominion over him.
Thou wilt show me--guide me to attain.
the path of life--or, "lives"--the plural denoting variety and abundance--immortal blessedness of every sort--as "life" often denotes.
in thy presence--or, "before Thy faces." The frequent use of this plural form for "faces" may contain an allusion to the Trinity (Num 6:25-26; Psa 17:15; Psa 31:16).
at thy right hand--to which Christ was exalted (Psa 110:1; Act 2:33; Col 3:1; Heb 1:3). In the glories of this state, He shall see of the travail (Isa 53:10-11; Phi 2:9) of His soul, and be satisfied.