Who is the man who desireth life? The prophet does not inquire if there be any man so disposed, as if all men voluntarily brought upon themselves the miseries which befall them; for we know that all men without exception desire to live in the enjoyment of happiness. But he censures severely the blindness and folly which men exhibit in the frowardness of their desires, and the vanity of their endeavors to obtain happiness; for while all men are seeking, and eagerly intent upon acquiring what is for their profit, there will be found scarcely one in a hundred who studies to purchase peace, and a quiet and desirable state of life, by just and equitable means. The prophet therefore admonishes his disciples, that nearly the whole world are deceived and led astray by their own folly, while they promise themselves a happy life from any other source than the divine blessing, which God bestows only upon the sincere and upright in heart. But there is in this exclamation still greater vehemence, the more effectually to awaken dull and drowsy minds to the course of this world; as if he had said, Since all men earnestly desire happiness, how comes it to pass, that scarcely any one sets himself to obtain it, and that every man, by his own fault, rather brings upon himself various troubles?

What man is he that desireth life? - That desires to live long. All people naturally love life; and all naturally desire to live long; and this desire, being founded in our nature, is not wrong. Life is, in itself, a good - a blessing to be desired; death is in itself an evil, and a thing to be dreaded, and there is nothing wrong, in itself, in such a dread. Equally proper is it to wish not to be cut down in early life; for where one has before him an eternity for which to prepare, he feels it undesirable that he should be cut off in the beginning of his way. The psalmist, therefore, does not put this question because he supposes that there were any who did not desire life, or did not wish to see many days, but in order to fix the attention on the inquiry, and to prepare the mind for the answer which was to follow. By thus putting the question, also, he has implicitly expressed the opinion that it is lawful to desire life, and to wish to see many days.
And loveth many days - literally, "loving days." That is, who so loves days, considered as a part of life, that he wishes they may be prolonged and multiplied.
That he may see good - That he may enjoy prosperity, or find happiness. In other words, who is he that would desire to understand the way by which life may be lengthened out to old age, and by which it may be made happy and prosperous? The psalmist proposes to answer this question - as he does in the following verses, by stating the results of what he had experienced and observed.

What man is he that desireth life - He who wishes to live long and to live happily, let him act according to the following directions. For a comment upon this and the four ensuing verses, see the notes on 1-Peter 3:10-12 (note).

What man [is he that] desireth life, [and] loveth [many] days, that he may (i) see good?
(i) Seeing all men naturally desire happiness, he wonders why they cast themselves willingly into misery.

What man is he that desireth life?.... Every man desires life, even a natural life; it is more desirable than all things in it; especially an healthful life, without which the blessings and mercies of life cannot be comfortably enjoyed; and still more a life of prosperity; life, with an affluence of good things, and even a long one: though it may be rather that a spiritual life is here meant, and a comfortable one; a life free from the remorses of a guilty conscience, from the fear of hell, damnation, and wrath; from the bondage of the law, and the dread of death; a life of faith on Christ, and communion with him; and a life of sobriety, righteousness, and holiness; and perhaps it may be best of all to understand it of eternal life, which is life eminently and emphatically; it follows,
and loveth many days; that is, good ones; as they are interpreted in 1-Peter 3:10; not of this life, for the days of it are evil, and especially when they are lengthened out; the days of old age, Ecclesiastes 12:1; unless the days of the son of man, the days of enjoying the presence of God in his house and ordinances, should be intended; though rather the good and many days of eternity, even length of days, for ever and ever, in which will be fulness of joy, and never ceasing and never fading pleasures;
that he may see good; there is good to be seen and enjoyed in this life, which if the saints did not believe they should see and enjoy, they would often faint; and this good lies in the participation of the blessings of grace, and in fellowship with Father, Son, and Spirit: but the great and lasting good to be seen and enjoyed is in the world to come, when God shall be all in all, be seen as he is, and the saints shall inherit all things.

What man--Whoever desires the blessings of piety, let him attend.

Life - A long and happy life, begun in this world and continued for ever in the next. Good - In which he may enjoy good, prosperity or happiness.