For thus said the Lord GOD, the Holy One of Israel: This verse begins with a quote frame for God’s speech that is similar to the one in verse 12. It adds the Lord GOD to the expression (see the comments on 3.15). The Hebrew particle ki rendered For is an emphatic marker here, which may be rendered “Indeed” or “Truly.” Good News Translation omits it, which is acceptable.

In returning and rest you shall be saved: When the people of Judah trust in God, they are saved. The Hebrew noun for returning comes from a root meaning “to turn,” so New International Version says “repentance,” and New Jerusalem Bible has “conversion.” Others believe it has the sense of tranquility here since it is paired with rest; for example, Revised English Bible combines them, saying “calm detachment.” We believe returning is a call to turn back from the treaty with Egypt, while rest calls for trust in God, which is clear in the next line. You shall be saved refers to rescue from inevitable shame (verses 3-5).

In quietness and in trust shall be your strength: This line is parallel to the previous one. A quiet trust in God is the source of true power. The word pair quietness and trust supplements the notion of rest. Good News Translation and Bible en français courant add the object of the trust by saying “trust in me,” which may be helpful for other languages.

Although Revised Standard Version uses the future tense for God’s words, this may not be the best option. The Hebrew verbs rendered shall be saved and shall be are in the imperfect form, which expresses facts that are always true. In English the present tense is better here, as in Revised English Bible, which says “In calm detachment lies your safety, your strength in quiet trust” (similarly New International Version, New Jerusalem Bible).

For the translation of this verse consider the following examples:

• This is what Yahweh, my Master, the Holy One of Israel, says:
“In turning back and in calmness is your victory,
in acceptance and trust lies your power.”

• Yahweh, my Lord, Israel’s Holy One, says:
“When you turn back and are calm, you have victory;
when you submit and trust [in me], you can be mighty.”

Instead of calmly trusting in Yahweh, the people of Judah plan to do the opposite. They plan to ride the swift horses from Egypt to flee from their pursuing enemies.

And you would not: The people refused to accept the LORD’s words to trust in him. Their negative response confirms they were rebellious (verses 1, 9). The connector And is better rendered “But” (Good News Translation, New International Version, Revised English Bible) to express the contrast here. You would not refers to unwillingness and stubbornness. New International Version and New Jerusalem Bible say “you would have none of it,” which expresses it well in English.

But you said, “No! We will speed upon horses”: The connector but (literally “and”) may be omitted if the preceding clause begins with “But” to express the contrast here. The verb said may be rendered “thought.” No! marks the people’s rejection of Yahweh’s call for patient trust in him. Instead, they arrogantly claim that they will be able to flee (speed) on horseback. The Egyptians were famous for their horses and chariots (31.1). The people of Judah believe that under the terms of the treaty, Egypt will provide them with horses to escape the Assyrians. The Hebrew word for speed is nus and the word for horses is sus, so there is sound play here. For horses see 2.7.

Therefore you shall speed away: Speed away renders the same Hebrew verb as the one translated speed in the previous line. The people use this verb in a positive sense, but the prophet uses it negatively. He is using irony here, saying that they will flee in defeat before the Assyrians. Translators should try to use the same verb in both lines, making it clear that it has a negative sense the second time (see the examples below).

And, “We will ride upon swift steeds”: This is another claim made by the people of Judah. It is parallel to the first one. We will ride upon swift steeds is literally “Upon quick we will ride.” Revised Standard Version adds the word steeds (which is another word for horses) since it can be implied from the parallel claim. Revised English Bible says “We shall ride apace [that is, ride fast],” which is acceptable.

Therefore your pursuers shall be swift: The Hebrew verb rendered shall be swift comes from the same root as the one translated swift in the previous line. The people use it positively, but the prophet uses it negatively to say their pursuers will be equally swift. Translators should try to keep this wordplay. Revised English Bible does it by saying “Therefore swift will be the pace of your pursuers!”

Good News Translation renders the direct quotes of the people in verse 16 as indirect discourse. Other languages may find this helpful.

Translation examples for verses 15b-16 are:

• 15b But you have been unwilling to do so.
16 You said, “No! We will flee on horseback.”
[And I say:] So you will have to flee.
You also said, “We will ride swiftly away.”
[And I say:] So you will be pursued swiftly.

• 15b But you would have none of it.
16 You said, “No! We are going to flee on horseback”—
so you will flee away.
You also said, “We will ride swiftly”—
so your pursuers will be swift.

Quoted with permission from Ogden, Graham S. and Sterk, Jan. A Handbook on Isaiah. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here .