From Alec Motyer’s commentary on Isaiah 26:4 – “Faith is not a flash in the pan but a lifelong commitment, and it is a well-founded approach to life, not because of what it is (for it may be weak and wobbly) but because of the one in whom it reposes, for the LORD … is the Rock eternal. The LORD, the LORD is ‘Yah Yahweh’. The diminutive ‘Yah’ is a name of endearment (12:2; Exod. 15:2; Ps. 118:14) which most frequently appears in ‘Hallelujah’. The idiom (lit.) ‘in Yahweh is an everlasting rock’ means ‘Yahweh is the very essence of what an everlasting rock should be’ (cf. 17:2), durable, changeless and of saving efficacy (as in Exod. 17).” _{Motyer, J. Alec. 1999. Isaiah: An Introduction and Commentary. Vol. 20. Tyndale Old Testament Commentaries. Downers Grove, IL: InterVarsity Press.}

Think on it child of God, this is your God in Jesus Christ – your everlasting rock.