As the LORD of hosts lives: See the comments on 1 Kgs 1.29. These words function here to affirm the truth of what Elijah is saying.
The expression the LORD of hosts occurs for the first time in the Old Testament in 1 Sam 1.3 and the first time here in 1–2 Kings. The Hebrew is literally “Yahweh Sabaoth” (New Jerusalem Bible). The precise meaning of this title is not certain. “Sabaoth,” which is traditionally translated as “hosts,” may refer to (1) the armies of Israel (as in 1 Sam 17.45), (2) angelic beings (as in Psa 103.21; 148.2), or (3) heavenly bodies, that is, the stars (as in Isa 40.26). The general meaning of this title is clear, however. It designates the LORD as one who is an all-powerful ruler. Hence, some translations use the expression “the LORD Almighty” (Good News Translation, New International Version, Traduction œcuménique de la Bible), “the LORD All-Powerful” (Contemporary English Version), or “the LORD of the universe” (Parola Del Signore: La Bibbia in Lingua Corrente). Others say “the Lord of armies” (Louis Segond, La Bible Pléiade, Peregrino), “the Lord of heaven’s armies” (International Children’s Bible), or “the Lord of the armies of Israel” (Parola Del Signore: La Bibbia in Lingua Corrente in some passages, but not here). Many say “the LORD of hosts” (Revised Standard Version/New Revised Standard Version, Revised English Bible, New American Bible, New Jewish Publication Society’s Tanakh), even though the word “host” is no longer used in contemporary English to mean “army.” Translators are advised that it will probably be better to use a comprehensive word or expression like “Almighty” or “All-Powerful” rather than something with a narrower meaning like “armies.”
Before whom I stand: See the comments on the phrase “to stand before someone” in 1 Kgs 10.8.
I will surely show myself to him today is literally “indeed today I will be seen by him.” Show myself renders the same Hebrew verb translated “show yourself” in verse 1 (see the comments there). Since the pronoun him may possibly be understood as referring to the LORD in this context, several versions replace it with “the king” (Good News Translation) or “Ahab” (New International Version, New Century Version, Contemporary English Version, Nouvelle Bible Segond).
Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on 1-2 Kings, Volume 1. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here .