Exegesis:

eis hēn d’ an eiselthēte oikian lit. ‘into whatever house you go,’ but the relative hēn is not taken up in the main clause.

prōton legete ‘say first,’ i.e. before bringing your message.

eirēnē tō oikō toutō ‘peace to this house,’ a well known Hebrew greeting (cf. e.g. Judges 19.20). Here it refers to the peace that characterizes the Messianic kingdom.

Translation:

Whatever house you enter, or, ‘when you go into (or, set foot in) a house’ (cf. New English Bible, Sranan Tongo).

Peace be to this house, or, ‘may peace be given to this house,’ ‘may (the people in) this house receive peace,’ ‘may God give peace to (all of) you who are in this house’; or, since wishing peace is a form of blessing, ‘may God give you blessing, this whole household’ (Tzeltal), cf. also Tae’ 1933, lit. ‘pray-for those people that their life be well (a term for blessing).’ Where the optative mood can be expressed by position (as here in the Greek), or by an optative verbal form or particle, one may prepose a phrase like, ‘I want/wish that.’ For peace, here used with positive aspect, see on 1.79. — Renderings in the line of those just mentioned will have to be used even in the considerable number of languages where the expression concerned does not function as, or even resemble, a formula of salutation, but it may be possible then to hint at the functional meaning, e.g. by rendering the introductory “first say” by, ‘first say by way of greeting.’

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.