Isaiah 50:4,5

The relation of the Servant to Jehovah is that of a favourite disciple to his master; from Him he had learned the art of persuasive and consoling speech, and to Him he daily looks for the substance of his message. Comp. Isaiah 49:2 (the Servant's endowment with prophetic eloquence), and Isaiah 42:3 (the gentleness of his ministry).

the tongue of the learned a disciples" tongue (see ch. Isaiah 8:16), i.e. a disciplined tongue (R.V. "of them that are taught"). The stress laid on the Divine education of the Servant is connected with the fact that his ministry of consolation was almost a new departure in prophecy. In the hands of the earlier prophets the word of Jehovah had been like a hammer breaking the rock in pieces (Jeremiah 23:29) rather than a dew reviving the spirit of the humble.

thatI should know … weary A difficult clause. The verb rendered "speak in season" (-ûth) is unknown in Hebrew. The A.V., following the Jewish interpreters, takes it to be a denominative from the word for "time" (-çth), but that is an impossible etymology. The LXX. gives a similar sense (τοῦ γνῶναι ἡνίκα δεῖ εἰπεῖν λόγον) but based on a different text. Of the traditional interpretations the most suitable is perhaps that of the Vulg. and Aquila (which is followed by the R.V.): that I should know how to sustain the weary with a word. Modern authorities who adopt this rendering support it by an Arabic verb meaning "to help," which however is not an exact philological equivalent. Another Arabic analogy has suggested the translation "water" (i.e. "refresh"). It is impossible to get beyond conjecture, although the general sense is clear.

he wakeneth(sc. my ear) morning by morning (cf. Isaiah 28:19). A far simpler sentence results if we omit with Cheyne the first word of the Heb. (or with Duhm the first two words) as an uncorrected slip of a copyist, reading the adverbial expression with the following verb; thus: "morning by morning (or "in the morning") he wakeneth my ear to hear" &c.

as the learned after the manner of disciples.