Adam Clarke on Isaiah 42:19

As my messenger that I sent "As he to whom I have sent my messengers" - כמלכי אשלח kemalachey eshlach, ut ad quem nuncios meos misi. The Vulgate and Chaldee are almost the only interpreters who render it rightly, in consistence with the rest of the sentence, and in perfect agreement with the Hebrew idiom; according to which the ellipsis is to be thus supplied: כלאשר מלאכי אשלח kelaasher malachey eshlach; "As he to whom I have sent my messengers."

As he that is perfect "As he who is perfectly instructed" - See note on Isa 44:2 (note).

And blind as the Lord's servant "And deaf, as the servant of Jehovah" - For ועור veivver, and blind, we must read וחרש vecheresh, and deaf: κωφος, Symmachus, and so a MS. The mistake is palpable, and the correction self-evident, and admissible though there had been no authority for it.