Verse 20 is normally taken to contrast with verse 19, as shown by But. Not all languages need such a word, since the context shows the contrast clearly. Here as has the sense of “while,” as in “(But) while he was thinking….”

The verb considered (Good News Translation “thinking about”) appears in the New Testament only here and in 9.4 in the construction “thinking such evil things” (Good News Bible). Translators can do something similar to Good News Bible with phrases such as “planning this,” “planning to do this,” “putting his mind to this thing,” or “trying to decide what to do.”

Behold in Greek is related to the imperative form of the verb “Look!” It translates a Semitic form which may be rendered a number of ways, depending on the context. Quite often it is impossible to render it by any equivalent word in English. It may serve to enliven a narrative, to introduce new events, or even to add stress or emphasis. Perhaps it is best to think of it as an “attention-getter,” a device for calling attention to what follows.

Many languages do not use words like behold in this context. In such cases translators should not try to translate it here either. But in other languages, as for example in most African languages, such particles are an essential part of the discourse, and translators should use them not only here, but in many places where the text does not have them. The purpose here is to attract the attention of the readers: “Pay attention” or “Note this.”

The expression an angel of the Lord is used by Matthew also in verse 24; 2.13, 19; 28.2. An angel regularly represents God, either by bringing a message or by performing an action. The rendering of angel of the Lord can be affected by the manner translators have chosen to translate “angel.” For example, if “angel” has been translated elsewhere as “messenger of God,” then it will be strange to say in effect “a messenger of God of the Lord.” “Messenger of the Lord” will suffice in this context. If “spirit messenger” or “heavenly messenger” is the usual translation used, the phrase in this verse can be “spirit messenger of the Lord” or “heavenly messenger of the Lord.” In some languages the translation of “angel” is simply “messenger.” Then the expression “an angel (or, messenger) of the Lord” may unintentionally coincide with the term used for “preacher” or “prophet.” It is most likely that since in this verse the angel appears in a dream, readers will probably not think it was one of these human messengers. However, if testing shows that they do, translators will have to say here “heavenly (or, spirit) messenger of the Lord.”

It is sometimes necessary to indicate that of the Lord means it was the Lord who sent the angel, as in “an angel who came from the Lord” or “an angel whom the Lord sent.” If Lord is frequently used in a language for Jesus Christ, then translators can say “angel from God” in this verse.

In a dream is found only six times in the New Testament: Matthew 1.20; 2.12, 13, 19, 22; 27.19. In Judaism, dreams were acceptable means of divine revelation. Many languages distinguish between an ordinary dream and one that has a vision or supernatural oracle in it. The latter term would be the one to use here. It may be that instead of appeared … in a dream, it would be more natural to say “came to him while he was dreaming,” “came to him in the form of a dream,” or “showed himself to Joseph while he was dreaming.”

As indicated by the form of address, son of David, what is in focus here is the legal fatherhood of Joseph by which Jesus becomes a legitimate descendant of David. In some languages son of David will be correctly understood to mean a descendant, but in others, this phrase will make it seem that Joseph was the biological son of David, contrary to verse 16. In these languages translators can say “descendant of David,” “you who are descended from David,” “you who are from David’s family,” or “you whose ancestor was David.” Since the emphasis is on the fact that Joseph is from the royal line of David, it may be helpful to say “King David.”

Do not fear to take Mary your wife is ambiguous because in English it may seem to say that Mary is already his wife. The meaning is “do not be afraid to take Mary as your wife.” Good News Translation renders “do not be afraid to take Mary to be your wife,” and New English Bible “do not be afraid to take Mary home with you as your wife.” The reference, of course, is to the final phase in the marriage arrangement, whereby the husband takes his wife to his home. Barclay renders “do not hesitate to marry Mary.”

For that which is conceived in her is of the Holy Spirit is rendered by Good News Translation as “For it is by the Holy Spirit that she has conceived.” Die Bibel im heutigen Deutsch translates “since the child which she is expecting comes from the Spirit of God.” New English Bible and New American Bible render “It is by the Holy Spirit that she has conceived this child.” The most natural thing in some languages may be “It is the Holy Spirit that has caused her to be pregnant” or “She will have this baby because the Holy Spirit caused her to be pregnant.”

Although in Greek the definite article the is lacking before Holy Spirit, this is of no significance, because in the Greek of the New Testament it is difficult to establish clear rules for the use of the article. Moreover, the context clearly indicates that the reference is to God’s Spirit, that is, “the Holy Spirit.”

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .