Passage
When thou passest through the waters, I [will be] with thee; and through the rivers, they shall not overflow thee; when thou walkest through the fire, thou shalt not be burned, neither shall the flame kindle upon thee.
When thou passest through the waters, I [will be] with thee; and through the rivers, they shall not overflow thee; when thou walkest through the fire, thou shalt not be burned, neither shall the flame kindle upon thee.
Isaiah 43:1 But now thus saith Jehovah, that created thee, O Jacob, and he that formed thee, O Israel: Fear not, for I have redeemed thee, I have called [thee] by thy name; thou art mine.
Isaiah 43:2 When thou passest through the waters, I [will be] with thee; and through the rivers, they shall not overflow thee; when thou walkest through the fire, thou shalt not be burned, neither shall the flame kindle upon thee.
Isaiah 43:3 For I [am] Jehovah thy God, the Holy One of Israel, thy Saviour: I gave Egypt for thy ransom, Ethiopia and Seba for thee.
Isaiah 43:4 Since thou wast precious in my sight, thou hast been honourable, and I have loved thee; and I will give men for thee, and peoples for thy life.
The verse centers on "thou", "passest", "through", "waters", "thee", "rivers", and "shall". It is saying that the verse draws attention to "thou" and "passest", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "But now thus saith Jehovah that created..." into verse 3's "For I am Jehovah thy God the...", so "thou" and "passest" belong inside that flow. In Isaiah context, the local focus is the Holy One of Israel, judgment and restoration, the servant of the LORD, and Zion's hope.
A plain takeaway is to answer the verse's own emphasis on "thou" and "passest" with trust shaped by these words, not by a vague optimism outside the passage.