“This is what Yahweh says.” Isaiah 56:1-8 speaks about the Millennial Kingdom and what it takes to gain everlasting life and entrance into Christ’s kingdom on earth.
“do righteousness.” In this context, “righteousness” is doing what is right to God and others (see commentary on Matt. 5:6). The HCSB has, “Preserve justice and do what is right,” and that catches the meaning well.
“for my salvation is soon to come.” In this context, God’s coming salvation is the ultimate salvation that will come when the Messiah comes and rules the earth; the context is not about some short-lived deliverance from oppressive nations. The kingdom Christ will set up on earth will be salvation and deliverance such as the world has never seen, and it is often referred to by scholars as the “Millennial Kingdom” because it will last 1,000 years (Rev. 20:1-6). There were very few bright spots in history for Judah after the Assyrian attack that destroyed Israel (722 BC) in the time of Isaiah, so no historical time of deliverance would fulfil this prophecy in Isaiah 56.
[For more on the Millennial Kingdom, see Appendix 3, Christ’s Future Kingdom on Earth”].