In verses 10-13 Yahweh speaks to the Israelites. Good News Translation indicates this change in addressees by beginning verse 10 with “People of Israel.” Contemporary English Version is similar with “My people” (similarly Bible en français courant). These versions also add a stanza break to mark the change. Other languages may find these models helpful.
“You are my witnesses,” says the LORD: In the previous verse Yahweh invited the other nations to bring their witnesses to prove that they could predict world events accurately. Now he presents the Israelites as his own witnesses of what he has done. Says the LORD (literally “declaration of the LORD”) emphasizes that Yahweh is speaking, but it may be awkward in some languages to place such a clause here. It may be better to begin the verse with it (see the first example below). Good News Translation and Contemporary English Version assume that readers will know that Yahweh is still speaking, so they leave this clause implied.
And my servant whom I have chosen is parallel to the previous line. See the comments on 42.1.
That you may know and believe me and understand that I am He: Because the Israelites are Yahweh’s witnesses and servants, they know him, trust him, and recognize him as the only God. The three verbs here are closely related in meaning, emphasizing that the Israelites have a close relationship with Yahweh. For the clause I am He, see the comments on 41.4. Yahweh uses it here to claim he is the only God (so Good News Translation).
Before me no god was formed, nor shall there be any after me: In these two parallel lines Yahweh claims again that he is the only God. Like Revised Standard Version, many versions understand the Hebrew words rendered Before and after to have a temporal sense. However, in this context of Yahweh’s uniqueness as the only God, they have an exclusive sense (compare Exo 20.3), so they are better rendered “Besides” (Good News Translation) or “Apart from.” Both these words occur at the beginning of their lines in Hebrew, so they are emphatic. The Hebrew word for god is ʾel, which is the generic term for any divine being. In the present context it probably means “a god who is real.” The Hebrew verb rendered formed is the same one used in verse 1 to refer to the formation of the people of Israel. Here it points to the possible existence of other gods besides Yahweh, a possibility that these lines deny. It does not imply that Yahweh was created first since he has always existed. For the translation of these two lines we recommend an explicit reference to Yahweh’s position as the only God. They may be rendered “Besides me there have been no other gods, nor will there be any apart from me.” They may also be combined by saying “Apart from me, no other god will ever exist” or “… there will never be any other god.”
Translation examples for this verse are:
• Yahweh says, “My people, you are witnesses of what I have done,
and you are my chosen servant.
Thus you know and trust me,
and understand that I am He.
Apart from me there is no real god,
nor will any other god appear in the future.
• “You have witnessed my work,” says the LORD,
“and you are my servant whom I have chosen.
So now you know and trust me,
and understand that I am the only God.
There has never been any other god except me,
nor will there ever be another one in the future.
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 .