Как следует понимать еврейское выражение מִֽי־֭יִתֵּן (ми йиттен)? Является ли это идиомой, и если да, то что она означает?

В грамматиках используются такие термины, как желательный и/или желательный. מִֽי־֭יִתֵּן в основном похоже на междометие, чтобы ввести предложение, выражающее что-то желаемое. Более дословный перевод: «Кто даст / обеспечит?» Это вопросительное предложение, а не относительное предложение.

Грамматика

               2) Desiderative/Optative (especially in the phrase מִי־יִתֵּן, 
which tends to occur in poetry, particularly in the book of Job).

מִי־יִתֵּן מוּתִי אֲנִי תַחְתֶּיךָ
‍Would that I had died instead of you! (2 Sam 19:1); If only I had died … 
מִי־יִתֵּן אֱלוֹהַּ דַּבֵּר
Would that God might speak, … (Jb 11:5) 

Патнэм, ФК (2002). Вставка в Библию на иврите: Руководство для студентов по синтаксису библейского иврита (стр. 12). Квакертаун, Пенсильвания: Stylus Publishing.

§43.3. Factual (or WH-) Questions

These questions are introduced by the following interrogatives. 
In a verbal question the verb follows the interrogative. In a 
nominal clause the predicate follows the question:
...

Sometimes a fixed expression מִי יִתֵּן is used. This construction, which acts 
syntactically as an interjection, expresses a positive wish. (Cf. §45.3.)

בַּבֹּקֶר תֹּאמַר מִי־יִתֵּן עֶרֶב
‍In the morning you shall say: Would it were evening! (Deut. 28:67).‍

Ван дер Мерве, К., Ноде, Дж., Крезе, Дж., Ван дер Мерве, К., Ноде, Дж., и Крезе, Дж. (1999). Справочная грамматика библейского иврита (электронное издание, стр. 322-323). Шеффилд: Sheffield Academic Press.

                     THE OPTATIVE SENTENCE
...

§ 135. An interrog. sent. with מִי who? expresses a wish. 2 S. 23:15 מִי יַשְׁקֵנִי מַיִם 
O that I had water to drink! (lit., who will let me drink!). Ps. 4:7 מִי יַרְאֵנוּ טוֹב 
O that we saw some success! Nu. 11:4, 2 S. 15:4, cf. Mal. 1:10. — Particularly 
the phrase מִי יִתֵּן who will give? 2 S. 19:1 מִי יִתֵּן מוּתִי אֲנִי תַחְתֶּיךָ would that I had died 
for thee! Ex. 16:3. With impf., Job 6:8 מִי יִתֵּן תָּבוֹא שֶֽׁאֱלָתִי O that my request might 
come! Job 13:5; 14:13.

  Rem. 1. The opt. sense of לוּ, אִם, has arisen out of the conditional use; 
cf. Gen. 24:42, Ex. 32:32, where the transition is seen.
  Rem. 2. A rare opt. part. is אַֽחֲלֵי, אַחְלַי (out of אח and לי = לו), 2 K. 5:3, 
Ps. 119:5 (אָז in apod).
  Rem. 3. The consn. of מי יתן varies. (1</?LLS nbr?>) One acc., Jud. 9:29, 
Deu. 28:67, Ps. 14:7; 55:7, Job 14:4; 29:2 (suff.), 31:31, 35 (ptcp.). 
(2) Two acc., Nu. 11:29, Jer. 8:23; 9:1 (verbs of granting, 2 acc. § 78, 
R. 1; unless the consn. be who will set me in the wild, (in) a lodge, as 
Jos. 15:19, Jud. 1:15 where ארן might be acc. of place). (3) inf. cons. 
2 S. 19:1, Ex. 16:3; acc. and inf., Job 11:5 מִי יִתֵּן אֱלוֹהַּ דַּבֵּר that God would 
speak (anomalous arder perhaps due to emph. on God). (4) Simple impf., 
Job 6:8; 13:5; 14:13; impf. with vav, Job 19:23; vav conv. perf., Deu. 5:26 
O that this mind of theirs might be to them (always), to fear, &c. With perf. 
Job 23:3 (stative v.).

Дэвидсон, AB (1902). Введение в грамматику иврита Синтаксис иврита (3-е изд., стр. 183–184). Эдинбург: Т&Т Кларк.

§ 151. Desiderative Sentences.


a
A wish may be expressed not only by the simple imperfect (§ 107 n), 
cohortative (§ 108, especially with נָא § 108 c), jussive (§ 109; 
with נָא § 109 b), imperative (§ 110 a), perfect consecutive (§ 112 aa) 
or by a simple noun-clause (§ 116 r, note, and § 141 g) but also in the 
following ways:—
1. By exclamations in the form of interrogative clauses: especially 
sentences with מִי followed by the imperfect as being the mood of that 
which is still unfulfilled but possible, and hence also of that which 
is desired, e.g. 2 S 15:4 מִֽי־יְשִׂמֵ֫נִי שֹׁפֵט who maketh me judge? i.e. O that I 
were made judge! 1 S 20:10, 2 S 23:15. On the other hand, מִי with the 
perfect (Gn 21:7, Nu 23:10, 1 S 26:9, Is 53:1, &c.) or participle (Ps 59:8, 
Pr 24:22, &c.), rather expresses a rhetorical question, i.e. a denial, 
cf. § 150 d. Especially frequent is the use of מִֽי־יִתֵּן (prop. who gives?) 
to introduce all kinds of desiderative clauses (see under b).—In Mal 1:10 
the desiderative clause proper is co-ordinated with an interrogative 
clause, מִי גַם־בָּכֶם וְיִסְגּׄר דְּלָתַ֫יִם would that one were among you and would shut 
the doors, i.e. O that one would shut the doors!

b
Rem. Sometimes the original sense of מִֽי־יִתֵּן is still plainly discernible, 
e.g. Ju 9:29 מִֽי־יִתֵּן אֶת־הָעָם הַוֶּה בְיָדִי who gives this people into my hand? 
equivalent to, O that this people were given into my hand! cf. Ps 55:7. 
In these examples, however, מִֽי־יִתֵּן is still equivalent to O had I! and in 
numerous other instances the idea of giving has entirely disappeared, מִֽי־יִתֵּן 
having become stereotyped as a more desiderative particle (utinam). Its 
construction is either—
(a) With the accusative (in accordance with its original meaning) of a 
substantive, Dt 28:67 would that it were even!… morning! Ju 9:29, Ps 14:7 
(537), 55:7; with an accusative and a following infinitive, Jb 11:5; with 
two accusatives, Nu 11:29, Jer 8:23; with the accusative of an infinitive, 
Ex 16:3, 2 S 19:1 מִֽי־יִתֵּן מוּתִי אֲנִי תַחְתֶּ֫יךָ would that I had died for thee 
(for אֲנִי cf. § 135 f); of a participle, Jb 31:35; of a personal pronoun 
(as a suffix), Jb 29:2 (with a following כְּ; but מִֽי־יִתְּנֵ֫נִי Is 27:4 and Jer 9:1 
with a following accusative is not simply equivalent to מִֽי־יִתֵּן לִי, but is 
properly who endows me with, &c.; cf. § 117 ff).—With a still greater 
weakening of the original meaning מִֽי־יִתֵּן is used with an adjective in Jb 14:4 
could a clean thing but come out of an unclean! i.e. how can a clean thing 
come, &c.; similarly in Jb 31:31 who can find one that hath not been satisfied!

Гезениус, FW (1910). Грамматика иврита Гезениуса . (E. Kautzsch & SAE Cowley, ред.) (2-е английское изд., стр. 476–477). Оксфорд: Кларендон Пресс.