Faith is the Assurance of Things Hoped For

Hebrews 11:1 "Now faith is the assurance of things hoped for, the conviction of things not seen."
Faith is assured.
Hebrews 3:6 "But Christ was faithful as a Son over His house, whose house we are if we hold fast our confidence and the boast of our hope firm until the end."

Hebrews 3:14 "For we have become partakers of Christ, if we hold fast the beginning of our assurance firm until the end."

So assurance is confident and boasts of the hope firm until the end.

Rom 11:22 Continue in His kindness or you will be cut off.
1 Cor 15:2 Your are saved if you hold fast the word which I preached to you (if you don't hold fast) unless you believed in vain.

Quiet confidence, trusting in quietness
assured, faith rests instead of striving.
To be assured is t know without a doubt.
Assurance on sure foundation of Scripture. Let your mind be full of the Scripture of God.