Gesenius' Hebrew Grammar/37. The Interrogative and Indefinite Pronouns
a 1. The interrogative pronoun is מִי who? (of persons, even before plurals, Gn 33, Is 60, 2 K 18, and sometimes also of things Gn 33, Ju 13, Mi 1; cf. also בַּת־מִי whose daughter? Gn 24; לְמִי to whom? אֶת־מִי whom?)—מָה, מַה (see b) what? (of things).—אֵי־זֶה which? what?
b The form מַהּ, מַּ, &c. (followed by Dageš forte conjunct.: even in יְ, Hb 2, &c., against § 20 m) may be explained (like the art. הַּ § 35 l, and וַּ in the imperf. consec.) from the rapid utterance of the interrogative in connexion with the following word. Most probably, however, the Dageš forte is rather due to the assimilation of an originally audible ה (מַהּ, as Olshausen), which goes back through the intermediate forms math, mat to an original mant: so W. Wright, Comparative Grammar, Cambridge, 1890, p. 124, partly following Böttcher, Hebräische Grammatik, § 261. A ground-form mant would most easily explain מָן (what?), used in Ex 16 in explanation of מָן manna, while מַן is the regular Aramaic for who. Socin calls attention to the Arabic mah (in pause with an audible h: Mufaṣṣal, 193, 8). Observe further that—
c (a) In the closest connexion, by means of Maqqeph, מַה־ takes a following Dageš (§ 20 d), e.g. מַה־לָּךְ what is it to thee? and even in one word, as מַלָּכֶם what is it to you? Is 3; cf. Ex 4, Mal 1, and even before a guttural, מהם Ez 8 Kethîbh.
d (b) Before gutturals in close connexion, by means of Maqqeph or (e.g. Ju 14, 1 S 20) a conjunctive accent, either מַה is used with a virtual strengthening of the guttural (§ 22 c), so especially before ה, and, in Gn 31, Jb 21, before זן—or the doubling is wholly emitted. In the latter case either (cf. § 35 e–k) ă is fully lengthened to Qames (so always before the ה of the article, except in Ec 2; also before הֵ֫מָּה, הֵ֫נָּה, and so ה (Hb 2), א (2 S 18, 2 K 8), ע (Gn 31, 2 K 8), or modified to Seghôl, especially before עָ, חָ, and generally before הָ. The omission of the strengthening also takes place as a rule with ה, ח, ע, when they have not Qameṣ, and then the form is either מָה or מֶה, the latter especially before ח or ע, if Maqqeph follows.
e The longer forms מָה and מֶה are also used (מֶה even before letters which are not gutturals) when not connected by Maqqeph but only by a conjunctive accent. As a rule מָה is then used, but sometimes מֶה when at a greater distance from the principal tone of the sentence, Is 1, ψ 4. (On מֶה in the combinations כַּמֶּה, בַּמֶּה, and even לָ֫מֶה, 1 S 1, cf. § 102 k and l.)
f (c) In the principal pause מָה is used without exception; also as a rule with the smaller disjunctives, and almost always before gutturals (מֶה only in very few cases). On the other hand, מֶה more often stands before letters which are not gutturals, when at a greater distance from the principal tone of the sentence, e.g. 1 S 4, 15, 2 K 1, Hag 1 (see Köhler on the passage), ψ 10, Jb 7; cf., however, Pr 31, and Delitzsch on the passage.
g 2. On מִי and מָה as indefinite pronouns in the sense of quicunque, quodcunque, and as relatives, is qui, id quod, &c., see § 137 c.