Exegesis:

houtos estin peri hou gegraptai ‘this is he concerning whom it is written.’ gegraptai does not imply a literal quotation.

kataskeuazō, cf. on 1.17.

emprosthen sou ‘before you,’ either temporal (‘before your arrival’) or local (‘in front of you’), preferably the latter.

Translation:

This is he of whom it is written. The substitution of a noun or of the name ‘John’ is sometimes preferable; for the relative clause cf. on 4.4; hence, e.g. ‘John is the one of whom it is written,’ ‘about this man Scripture has said, or, a prophet has written,’ etc.

If I send my messenger, or, ‘my sent-one,’ would become tautological, one may say, ‘I send (or, order to go) my servant.’ The source of the statement may have to be indicated, e.g. ‘God says, “I send…” .’

Before thy face, or, ‘(to go/walk) in front of you,’ ‘to be herald before you’ (Javanese), ‘your forerunner’ (Batak Toba)

Who shall prepare thy way, cf. on 3.4.

Before thee (not found in 3.4 and Mk. 1.2) is semantically less important than the synonymous phrase ‘before thy face’ is in its clause, since it only expresses what is already implied in the preceding part of the sentence. It is best taken as attributive to ‘way,’ e.g. “the road ahead of you” (An American Translation), ‘the way that runs on in front of you.’ Simply to say, ‘prepare your way, or the way for you’ may be necessary in some cases, but does not do full justice to a feature that is characteristic of Luke’s wording here.

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.