Verse 3 is an interesting conclusion to the triumphant theme of verses 1 and 2. When the Lord promises the benefits of this triumphal reign, he does not promise wealth, he does not promise power, he promises rest. Wealth and power might be part of the reign of the ultimate king, but the benefit for his people is their rest, not their revenge.
In the symbolic sense, this promise is that made for those who follow the Lord in this life, that we will enter into his rest, that the hard labors will be over. This should not imply a life of idleness, but one removed from the painful parts of agency. When we have accomplished the purposes of this earth. and the end of its function has come for us, the way we have used our agency in the past will place us into a position where we will have made the hard decisions, and have become exalted, exalted in one sense in that we will be above the travails of this earth and its consequences of the use of agency here.
Historical: "Historically, these verses were fulfilled when Cyrus the Great of Persia issued an order allowing all captive peoples in Babylon to return to their place of origin. The first group of Jews returned in 538 BC and started to rebuild Jerusalem and Judea. Another great exodus of Jews began in 520 BC, and the group eventually was able to rebuild the walls of Jerusalem, the city itself, and the temple. Later, under the Maccabees (167-70 BC), the Jews enjoyed autonomy and prosperity, being so successful that they began to proselyte other people in the area and to grow in numbers. Indeed, the body of Jews grew into the millions by the time of Christ; while Babylon became desolate, Judea flourished." (Ludlow 1982, p. 186.)