Wherewithal - This begins the second portion of the psalm, extending to Psalms 119:16, in which all the verses begin with the second letter of the Hebrew alphabet (ב b), indicated in our translation by the word Beth. These names of the letters, inserted for convenience, are no part of the psalm, as it is not so marked in the original. This mode of indicating the divisions of the psalm is special to our version. It is not in the Septuagint, the Latin Vulgate, or the German versions. The word wherewithal means “by what” (Hebrew); that is, What means shall a young man adopt by which he may “cleanse his way?” it indicates a state of inquiry. The case supposed is that of a young man pondering the question how he may be saved from the corruptions of his own heart, and escape the temptations to which he is exposed in early years, and lead a pure and upright life. There can be no more important inquiry for one just entering on the journey of life; there can be found nowhere a more just and comprehensive answer than is contained in this single verse. All the precepts of ancient and modern wisdom, all the teachings of pagan morality and religion, and all the results of the experience of mankind, could furnish nothing in addition to what is here suggested. The world has no higher wisdom than this by which to guide a young man, so that he may lead a holy life.
Shall a young man - The remark here might be applied also to those who are in middle life, or even to those who are in more advanced years, but it is applied here especially to the young, because it may be supposed that in the other cases the matter may be regarded as settled by experience; because to the young, as they commence life, the inquiry is so momentous; and because it is a question which it may be supposed will come up before the mind of every young man who has any right aspirations, and any proper conception of the dangers which encompass his path.
Cleanse his way? - Make his course of life pure and upright. The language does not necessarily imply that there had been any previous impurity or vice, but it has particular reference to the future: not how he might cleanse himself from past offences, but how he might make the future pure. The inquiry is, how he might conduct himself - what principles he could adopt - under what influence he could bring himself - so that his future course would be honest, honorable, upright.
By taking heed thereto ... - The word “thereto” is not in the original. The Hebrew is, “To keep according to thy word;” or, “in keeping according to thy word.” Prof. Alexander supposes that this means “to keep it (his way) according to thy word;” and that the whole is a question - “How may a young man so cleanse his way as to keep it according to thy word?” - and that the answer to the question is to be found in the general strain of the psalm, or in the general principles laid down in the psalm. But it is clear that the answer to the question must be found in the verse, or not found at all; and the most natural construction is that in our translation. So DeWette renders it: “How can a young man walk guiltless? If (or, when) he holds (or, keeps) himself according to thy word.” The meaning clearly is If he governs himself according to the law of God - if he makes that law the rule of his life and conduct, he would be enabled to do it. All other things might fail; this rule would never fail, in making and keeping a man pure. The more principles of common honesty, the principles of honor, the considerations of self-interest, the desire of reputation - valuable as they may be - would not constitute a security in regard to his conduct; the law of God would, for that is wholly pure.