Exodus 4:10-12: Moses, Might in Word? or Slow of Speech?

Verse 10:[1] And Moses said unto the LORD, O my Lord, I am not eloquent (Heb. a man of words[2]), neither heretofore (Heb. since yesterday, nor since the third day[3]), nor since thou hast spoken unto thy servant: but (Ex. 6:12; Jer. 1:6) I am slow of speech, and of a slow tongue.

[I beseech[4]] Or, I beg: that is to say, Spare me, do not send me (Menochius, Lapide). It is an adverb of entreaty (Rivet).

[בִּי] O Lord: verbatim, for my sake (Rivet), or, in my case, or, my Lord (Oleaster). See on Genesis 43:20.[5]

[Not eloquent] Hebrew: not a man of words:[6] Symmachus:[7] οὐκ εὔλαλος, that is, not able to speak fluently (Drusius, thus Vatablus, Fagius). It is proper that those that are about to speak to princes be of such a sort (Fagius, Vatablus). Not suitable (Septuagint). I do not have good pronunciation (Arabic). Hence Moses was βραδύγλωσσον, that is, slow of speech, says Lucian in Philopatris. There was chaos and night…and God removed this confusion by his word alone, ὡς ὁ βραδύγλωσσον ἐπεγράψατο, as the one slow of speech wrote (as Moses wrote) (Gataker).

[From yesterday and the day before yesterday, etc.] That is, Hitherto. The Greeks use χθὲς καὶ πρώην, yesterday and the day before yesterday, only of a recent even (Grotius). It is a Hebraism, that is, I have never been eloquent (Fagius, Vatablus, Menochius). What follows teaches that this is the sense (Vatablus).

[Even from the time that thou didst speak, etc.] That is, By thine address I have not become more eloquent (Rivet). A