אֲשֶׁ֤ר חִצָּיו֙ שְׁנוּנִ֔ים וְכָל־קַשְּׁתֹתָ֖יו דְּרֻכ֑וֹת פַּרְס֤וֹת סוּסָיו֙ כַּצַּ֣ר נֶחְשָׁ֔בוּ וְגַלְגִּלָּ֖יו כַּסּוּפָֽה׃
Whose arrows are sharp, And all their bows bent; Their horses’hoofs shall be counted like flint, And their wheels like a whirlwind;
Rashi on Isaiah
like flint Jonathan renders: like a rock, similar to צור.
Ibn Ezra on Isaiah
כצר Like flint; comp. צורים flint39A. V., Sharp. (Jos. 5:3); the form of the noun varies.40From the same root two nouns can be constructed of different forms, but having the same meaning, like צר and צור flint; there is, according to I. E., no standard for the inflexion of the noun as there is for the verb : all verbs are conjugated after פעל.