Passage
Trust ye in Jehovah for ever, For in Jah Jehovah <FI>is<Fi> a rock of ages,
Trust ye in Jehovah for ever, For in Jah Jehovah <FI>is<Fi> a rock of ages,
Isaiah 26:2 Open ye the gates, that enter may a righteous nation, Preserving stedfastness.
Isaiah 26:3 An imagination supported Thou fortifiest peace--peace! For in Thee it is confident.
Isaiah 26:4 Trust ye in Jehovah for ever, For in Jah Jehovah <FI>is<Fi> a rock of ages,
Isaiah 26:5 For He bowed down the dwellers on high, A city set on high He maketh low, He maketh it low unto the earth, He causeth it to come unto the dust,
Isaiah 26:6 Tread it down doth a foot, Feet of the poor--steps of the weak.
The verse centers on "trust", "jehovah", "ever", "rock", and "ages". It is saying that the verse draws attention to "trust" and "jehovah", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 3's "An imagination supported Thou fortifiest peace--peace For..." into verse 5's "For He bowed down the dwellers on...", so "trust" and "jehovah" 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 "trust" and "jehovah" with trust shaped by these words, not by a vague optimism outside the passage.