The structure of this verse is quite complex. There are two linked statements. The first comprises two negative conditions and two consequences. The second asserts that one of the consequences is already fulfilled because one of the negative conditions is in fact true.
The two negative conditions are If you will not listen and if you will not lay it to heart to give glory to my name. For the phrase translated lay it to heart, compare the similar but not identical phrases in Hag 1.5, 7; 2.15, 18. The content of what the priests are required to do is to give glory to my name, which makes clearer the meaning of the “command” in verse 1. To give glory means to “praise” or “honor,” and my name is a common Hebrew way of referring to the LORD himself (compare 1.6, 11, 14). Thus Good News Translation has “You must honor me.” In using this construction, Good News Translation has transformed one of the conditions into a command. This may be a useful example in some other languages also.
The formula says the LORD of hosts has a function of emphasis at this point. In languages where it would be unnatural to include it here, it may be preferable to incorporate it into verse 1 as Good News Translation has (also Contemporary English Version, Bible en français courant, Die Bibel im heutigen Deutsch). Translators should note that the formula occurs again at the end of verse 4, where it concludes the first subsection of 2.1-9.
The two consequences are then I will send the curse upon you and I will curse your blessings. The first clause I will send the curse upon you is probably a conscious reference to Deut 28.20, where the “curse” referred to a “disaster” or “calamity.” The presence of the definite article the suggests that the reference is to a curse already known to the priests. The Hebrew verb translated I will send is rather strong, and in some languages it may be rendered as “I will hurl” or “I will fling” (compare Traduction œcuménique de la Bible je lancerai contre vous “I will throw against you”). I will send the curse upon you may alternatively be translated as “I will cause a terrible thing [or, calamity] to happen to you.”
In the second consequence clause I will curse your blessings, it is not certain what blessings are meant. Some scholars think the privileges of the priesthood are meant, including not only the honor of leading worship, but also the material benefits such as receiving tithes and portions of sacrificial animals. Others see a reference to the words of blessing (Num 6.22-27) which the priests used in public worship. While this is certainly included, translators would do well to choose a rendering that is not limited to just a set form of words, as is Contemporary English Version “when you give a blessing, I will turn it into a curse.” On the other hand, Good News Translation “I will put a curse on the things you receive for your support” probably focuses too much on the material aspect, though this was also in view.
The second statement in the verse is indeed I have already cursed them, because you do not lay it to heart. The existing disobedience of the priests, as described in 1.6-8 and 12-13, has already meant that their blessings are not endorsed by the LORD. If material goods are in view, then obviously when the priests accepted inferior animals for sacrifice, their own portions were also inferior. If words of blessing are in view, then the words of the priests to the worshipers were proving ineffective. The Hebrew suffix translated them is actually singular, but since blessings is the only possible noun the suffix could refer to, the plural them is justified in translation. The first clause of the second statement may also be translated in a way similar to Contemporary English Version “In fact, I have already done this,” where “this” refers back to “turn it into a curse.”
Because you do not lay it to heart: This clause makes it clear that the second of the two conditions earlier in the verse is actually fulfilled. The priests do not in fact honor the LORD as they should, and so the curse has already begun to take effect. In some languages there may be an idiom to translate lay it to heart; for example, “receive it with one heart.” In other languages it may be more natural to express this clause in a positive form, such as “you ignore [or, look down on] my commands.”
Quoted with permission from Clark, David J. & Hatton, Howard A. A Handbook on Malachi. (UBS Helps for Translators). New York: UBS, 2002. For this and other handbooks for translators see here .