Yea, if thou criest after knowledge, [and] (c) liftest up thy voice for understanding;
(c) Meaning that we must seek the knowledge of God with care and diligence.

Yea, if thou criest after knowledge,.... Of God, Christ, and the Gospel; not only bow the ear and bend the mind to these things, but importunately and fervently pray for them; not only attend the ministry of the word by men, but cry to God to give the Spirit of wisdom and revelation in the knowledge of divine and spiritual things; which supposes some sense of a want of it, an hearty desire for it, having some apprehension of the worth and value of it; and that it is to be had, as there is indeed great reason to hope for and expect it, James 1:5;
and liftest up thy voice for understanding; for Christ, who is understanding as well as wisdom, Proverbs 8:14; or rather for an understanding of the Gospel and the mysteries of it, which men do not naturally understand; and for which there must be an understanding given, or the eyes of the understanding must be enlightened; or Christ, by his spirit and grace, must open the understanding, that it may understand these things; which is granted to those who lift up their voice in prayer for it.

Yea, if--literally, "When if," that is, in such a case.
knowledge--or, "discrimination."
understanding--as in Proverbs 2:2.

Instead of כּי אם there is an old אל תקרי
(Note: Regarding this formula, see Strack's Prolegomena, pp. 66-70.)
(read not so, but thus), כי אם (if thou callest understanding mother), which supposes the phrase כי אם (lxx) as traditional. If אם were intended (according to which the Targ. in the Bibl. rabbinica, but not in Norzi's text, translates), then 3b would correspond; vid., Proverbs 7:4, cf. Job 17:14. Thus: Yea, if thou callest for understanding, i.e., callest her to thee (Proverbs 18:6), invitest her to thee (Proverbs 9:15). The ק of בּקּשׁ is, with the exception of the imper. (e.g., בּקּשׁוּ), always without the Dagesh. Proverbs 2:4 belongs to the ideas in the Book of Job found in these introductory discourses, cf. Job 3:21, as at Proverbs 2:14, Job 3:22 (Ewald, Sprche, p. 49). חפשׂ (חפּשׂ), scrutari, proceeds, as חפס shows, from the primary meaning of a ditch, and is thus in its root-idea related to חפר (to dig, search out). In the principal clause of Proverbs 2:5 the 'יראת ה, as Psalm 19:10, is the fear of Jahve as it ought to be, thus the reverence which is due to Him, the worshipping of Him as revealed. 'ה and אלהים are interchanged as קדשׁים and 'ה at Proverbs 9:10. דּעת is knowledge proceeding from practice and experience, and thus not merely cognition (Kenntnis), but knowledge (Erkenntnis). The thoughts revolve in a circle only apparently. He who strives after wisdom earnestly and really, reaches in this way fellowship with God; for just as He gives wisdom, it is nowhere else than with Him, and it never comes from any other source than from Him. It comes (Proverbs 2:6) מפּיו (lxx erroneously מפּניו ylsuoe), i.e., it is communicated through the medium of His word, Job 22:22, or also (for λὀγος and πνεῦμα lie here undistinguished from one another) it is His breath (Book of Wisdom 7:25: ἀτμὶς τῆς τοῦ Θεοῦ δυνάμεως καὶ ἀπόῤῥοια τῆς τοῦ παντοκράτορος δόξης εἰλικρινής); the inspiration (נשׁמת) of the Almighty (according to Job 32:8) gives men understanding. In Proverbs 2:7, whether וצפן (Chethı̂b) or יצפּן (Kerı̂) is read, the meaning is the same. The former is the expression of the completed fact, as ἡτοίμασεν, 1-Corinthians 2:9, and is rightly preferred by lxx and Syr., for one reluctantly misses the copula (since the thought is new in comparison with Proverbs 2:6). לישׁרם should be written with the accent Dech. The Chokma-word (besides in Proverbs and Job, found only in Micah 6:9 and Isaiah 28:29) תּוּשׁיּה is a Hiphil formation (with the passing over of into , as in תּוּגה) from הושׁה (whence the pr. names יושׁה and יושׁויה) = (Arab.) wasy and âsy, to re-establish, to advance, Hiph. of ישׁה = ושׁה, to stand, and thus means furtherance, i.e., the power or the gift to further, and concretely that which furthers and profits, particularly true wisdom and true fortune.
(Note: I was formerly in error in regarding the word as a Hophal formation, and in assigning to it the primary signification of being in a state of realized existence, of reality, in contradistinction to appearance only. The objection of J. D. Michaelis, Supplem. p. 1167, Non placent in linguis ejusmodi etyma metaphysica, etc., does not apply here, since the word is a new one coined by the Chokma, but all the shades of meaning are naturally derived from the fundamental signification "furtherance" (cf. Seneca, Deus stator stabilitorque est). "תושׁיה, from Arab. âsy and wasy, to further by word and deed, to assist by counsel and act, to render help, whence the meanings auxilium, salus, and prudens consilium, sapientia, easily follow; cf. Ali's Arab. proverb, "He furthers thee, who does not trouble himself about thee.")
The derivation from ישׁ (Proverbs 8:21) is to be rejected, because "the formation would be wholly without analogy, so much the more because the י of this word does not represent the place of the ו, as is seen from the Arab. l-ys and the Syr. lyt" (Fl.);
(Note: The Arab. ‛aysa (almost only in the negative la-ysa = לא ישׁ), of the same signification as ישׁ, with which the Aram. אית (איתי) is associated, presupposes an ‛âsa (= ‛âssa), to be founded, to found, and is rightly regarded by the Arabs as an old segolate noun in which the verbal force was comprehended.)
and the derivation of ושׁה = שׁוה, to be smooth (Hitzig), passes over without any difficulty into another system of roots.
(Note: The Arab. wsy and swy are confounded in common usage (Wetstein, Deutsch. Morgenl. Zeitschr. xxii. 19), but the roots וש and שו are different; וש and אש, on the contrary, are modifications of one root.)
In the passage under consideration (Proverbs 2:7), תּוּשׁיּה signifies advancement in the sense of true prosperity. The parallel passage 7a clothes itself in the form of an apposition: (He) a shield (מגן, n. instr. of גּנן, to cover) for הלכי תּם, pilgrims of innocence (Fl.), i.e., such as walk in the way (the object-accus., as Proverbs 6:12, for which in Proverbs 10:9 בּ) of innocence. תּם is whole, full submission, moral faultlessness, which chooses God with the whole heart, seeks good without exception: a similar thought is found in Psalm 84:12. לנצר, 8a, is such an inf. of consequence as להקשׁיב (Proverbs 2:2), and here, as there, is continued in the finite. The "paths of justice" are understood with reference to those who enter them and keep in them; parallel, "the way of His saints" (חסיד, he who cherishes חסד, earnest inward love to God), for that is just ארח־צדקה (Proverbs 12:28): they are הלכי צדקות (Isaiah 33:15). Instead of the Mugrash, the conjunctive Tarcha is to be given to ודרך.

Criest - To God, the only giver of it.