Updated: May 29, 2018
The יָהּ/Jah, from consummate Comeliness. That this is a divine Name, we are expressly taught in Psalm 68:4, בְּיָ֥הּ שְׁמ֗וֹ, by His name Jah.
For the illustration of the use of the letter ב/in/by, in this passage set before the divine Name יָהּ/Jah, the following observation of the illustrious SCHULTENS on Proverbs 3:26, will be found to be advantageous, as it appears: The sense requires that בְכִסְלֶךָ, in thy confidence, be taken in that sense in which the Preposition ב/in with utmost frequency implies the inmost quality of a thing, or person; or the express and eminent character with which anything is marked and distinguished…. It is also common in the Sacred Books: in Ecclesiastes 7:12, בְּצֵ֥ל הַֽחָכְמָ֖ה בְּצֵ֣ל הַכָּ֑סֶף, wisdom is in a shade; silver is in a shade: in the place of, it is a shade, or something that overshadows, revives, covers…. And so also in this passage, Jehovah shall be in the firmness of thy loins: that is, Jehovah shall certainly be the very firmness of thy loins. And again on Proverbs 16:6, בְיִרְאַת, in fear/reverence: a little gem of eloquence, in the place of, the very fear of Jehovah…. A simple structure would have imparted, סוּר מֵרָע יִרְאַת יְהוָה, to depart from evil is the Fear/Reverence of Jehovah. בְיִרְאַת, in fear/reverence, now added a certain force, which means the same thing, and establishes and attests the very Character of the same. In a similar manner, בְּיָ֥הּ שְׁמ֗וֹ, by His name Jah, will signify that יָהּ/Jah is certainly His Name; יָהּ/Jah is His most peculiar Name, and exhibits the manifest and especially distinctive character, by which God deserves to be denominated.
α. According to most this Name is judged to be of the same origin and signification with יְהוָה/Jehovah; whether it be abbreviated from the Name יְהוָה/Jehovah, consisting of the first two letters of that Name, or by syncope it be contracted from the first and last letters of the Name יְהוָה/Jehovah: one or the other of which the most excellent Doctors of the Hebrews maintain, with NICHOLAS FULLER in BUXTORF’S Dissertatione de Nominibus Dei Hebraicis, which is the quinta Dissertationum philologico-theologicarum, § 34, with the Kabbalists also playing with the Number of the Letters; while they find both Names to make the same computation: namely, יהוה/YHWH makes twenty-six; and יָהּ/Jah also makes twenty-six, if the letters, יוֹד/yod and הֵא/he, be written out fully and resolved into number. Or at least it might derive from the same root הוה or היה, to be; whence also it is translated τὸ ὂν, the Being, in Questionibus et Responsionibus ad Orthodoxos, question L, among the works of JUSTIN Martyr. But, 1. it scarcely appears whence then that ה with the Mappiq (ּ) might has arisen. And, 2. it is probable from the conjunction of these two names, יָהּ יְהוָֹה, Jah Jehovah, that they differ in signification somewhat: namely, they are thus joined in Isaiah 26:4,בְּיָ֣הּ יְהוָ֔ה צ֖וּר עוֹלָמִֽים׃, in Jah Jehovah is everlasting strength. SCHINDLER, in his Lexico Pentaglotto, and CASTELL, in his Lexico Heptaglotto, derive יָהּ/ Jah from יָהָה; they maintain that this root is of the same signification as הָיָה, to be, and from this they think יָהּ/Jah to be formed, with the third letter cast aside and the second taking a Mappiq (ּ): which RUCKERSFELDER follows on Isaiah 38:11, who at the same time thinks that יָהּ/Jah and יְהוָה/Jehovah are able sometimes to be distinguished in their scriptural use in this sense, that he believes that יָהּ/ Jah leads us more to an expression of the true and living Existence of God, יְהוָה/Jehovah to the Constancy and Immutability of the same. But, while further inquiry concerning this determinate signification of the Name יָהּ/Jah is certainly warranted; I would certainly wish with Ruckersfelder that from another source some vestiges be indicated, from which one might gather that the root יָהָה existed in the same sense as הָיָה, to be, formerly among the Hebrews; but none of which things occur at all in the Hebrew Tongue, nor in cognate dialects.
β. The Most Illustrious LEUSDEN, Philologo Hebræo-Græco, Dissertation XXXI, § 4, 5, thinks that it is very probable, that יָהּ/Jah is the first or radical name, derived from no other; but, what it might denote by the force of the word, he does not think that it is evident with certainty to anyone.
γ. The Most Illustrious COCCEIUS, in his Lexico Hebraici, root יאה, thinks that it is able to be derived from the root יָאָה, to be fitting/ seemly, so that it might primarily denote God’s beauty, comeliness; which root occurs only once in the Old Testament, Jeremiah 10:7, כִּ֥י לְךָ֖ יָאָ֑תָה, for to thee doth it befit, where, nevertheless, 1. it is used not of that which it is fitting for God to offer; but of that which it is fitting to be offered to God by us: and, 2. that יָאָתָה, it is fitting, is able as easily to be derived from יָאַת, as from יָאָה, to be fitting: but, 3. especially the Most Illustrious SCHULTENS teaches that it is especially objected against this derivation, that thus the הּ is not able to be with the Mappiq (ּ), while that ה, in words quiescing in the third ה and their derivatives, is never mobile. Indeed, Cocceius tries to prove this by examples, for example, תֵּלַהּ, it fainted, in the future/imperfect, from לָהָה, to languish, in Genesis 47:13; נֺהַּ/lamentation, from נָהָה, to lament. But contrariwise the Most Illustrious SCHULTENS observes that, if תֵּלַהּ, it fainted, is from לָהָה, to languish, then the motion is attributed to the second radical, not the third; but to him the root is from יָלַהּ. That in this way נֺהַּ/lamentation from נָהָה, to lament, has clearly lost its third radical, with the second, as it is from its root, mobile, and therefore now to be marked with a Mappiq (ּ): see SCHULTENS’ Institutiones ad Fundamenta Linguæ Hebrææ ad regulam CXXXII, note ה, compared with note ד, pages 388, 389. But, that the matter here is not so very different, VRIEMOET, Adnotationibus ad Dicta classica Veteris Testamenti, part 1, chapter III, page 132, teaches to be able to be understood, if we say that the mobile א, after the quiescent ה has been dropped, in our יָהּ/Jah from יָאָה, to be fitting, is only changed into the mobile letter הּ of the same class and instrument. But in our judgment it is not necessary here to have recourse to a transposition of the same.
And so rather, δ. unto the same norm that we just now recited out of the Most Illustrious SCHULTENS, we think that יָהּ/Jah is best able to be derived from a word doubling its second radical ה, of which the second is here marked by a Mappiq (ּ) as mobile, with the third dropped; which reasoning I indicated above Schindler and Castell enter upon. And so the root will be יהה, but in the sense of comeliness, in which I do not doubt that the same was extant among the Hebrews from a root that is found among the Syrians, the final radical of which in a similar case with the ה is wont to be changed, and in their dialect denotes to be fitting: so that the signification of the Name יָהּ/Jah is thus going to be the same as that which the Most Illustrious Cocceius assigned to it; but in the derivation the Illustrious Man did not quite satisfy the analogy of the Language. I do not doubt that the signification that from this derivation agrees with the Name יָהּ/Jah squares with those passages of Sacred Scripture in which the same name occurs.
 Proverbs 3:26: “For the Lord shall be thy confidence (כִּֽי־יְ֭הוָה יִהְיֶ֣ה בְכִסְלֶ֑ךָ), and shall keep thy foot from being taken.” כֶּסֶל can signify loins or confidence.
 That is, the omission of sounds or letters from within a word.
 Nicholas Fuller (1557-1622) was an Anglican churchman, a learned divine, and a critic of considerable reputation. He excelled in the languages of the Scripture, and he applied his considerable talents to the resolution of Scripture difficulties.
 The numerical value of the letters: י = ten, ה = five, ו = six.
 The numerical value of the letters: י = ten, ו = six, ד = four, ה = five, א = 1.
 Valentine Schindler (died 1604) was a Lutheran Hebraist. He was Professor of Oriental Languages at Wittenberg and at Helmstadt. He composed a Polyglott Lexicon, consisting of Hebrew, Chaldean, Syriac, and Arabic.
 Edmund Castell (1606-1686) was an English orientalist. Castell helped Walton in the preparation of the Polyglott Bible. His great work was the Lexicon Heptaglotton Hebraicum, Chaldaicum, Syriacum, Samaritanum, Æthiopicum, Arabicum, et Persicum.
 Abraham Friedrich Rückersfelder (1727-1799) served as Professor of Theology at Deventer.
 Isaiah 38:11: “I said, I shall not see the Lord, even the Lord, in the land of the living (לֹא־אֶרְאֶ֣ה יָ֔הּ יָ֖הּ בְּאֶ֣רֶץ הַחַיִּ֑ים): I shall behold man no more with the inhabitants of the world.”
 Ezekiel 7:11: “Violence is risen up into a rod of wickedness: none of them shall remain, nor of their multitude, nor of any of theirs: neither shall there be wailing (נֹהַּ) for them.”