1 John 3:19

And this is how we will know that we are following [God's] truth, and will have assurance [of it] in our hearts and before God [as well].

John 13:35

If you love one another, then everyone will know by [observing] this that you are my disciples."

John 18:37

So, Pilate said to Him, "Are you a king, then?" Jesus answered, "You are [correct in] calling me a 'king.' This was the [very] purpose for which I was born and came into the world, that I should testify about the truth. Every person who wants [to know and obey] the truth listens to me."

Romans 4:21

and was fully convinced that what He had promised, He was able to carry out.

Romans 8:38

For I am convinced that neither death, nor [the trials of] life, nor [evil] angels, nor [evil] rulers, nor present or future [circumstances], nor [evil] powers,

2 Timothy 1:12

For I am suffering these things [See verse 8] for this reason [i.e., because of being a Gospel preacher]. Yet I am not ashamed because I know whom I have believed in [i.e., Jesus], and I am convinced that He is able to guard what I have entrusted to Him [i.e., Paul's spiritual well-being] until that day [i.e., the day of judgment].

Hebrews 6:10-11

For God is not [so] unjust as to forget the work you are doing and the love you have shown for Him, as you ministered to the saints [i.e., His holy people] and continue to minister [to them].

Hebrews 10:22

we should draw close [to God] with a sincere heart and a fully assured faith, having had our hearts sprinkled from a guilty conscience [See 9:13-14] and having had our bodies washed with clean water [i.e., in our immersion].

Hebrews 11:13

These people [all] continued to have faith until they died, [even though] they had not obtained [all] the things God had promised, but had [only] seen them and welcomed them from a distance. And they had confessed to being strangers and aliens on earth.

1 John 1:8

If we claim to have no sinful practices [in our lives], we are self-deceived and are not being truthful about the matter.

1 John 3:14

[For] we [can] know that we have passed out of [the realm of spiritual] death and into [spiritual] life, because we [show] love for the brothers [and sisters]. The person who does not love [them] continues to be [spiritually] dead.

1 John 3:21

Loved ones, if our hearts do not condemn us [i.e., because we are showing love by helping the needy], we can have boldness before God [in prayer for our own needs];

Treasury of Scripture Knowledge

Summary

And hereby we know that we are of the truth, and shall assure our hearts before him.

Bible References

Shall

1 John 3:21
Loved ones, if our hearts do not condemn us [i.e., because we are showing love by helping the needy], we can have boldness before God [in prayer for our own needs];
Hebrews 6:10
For God is not [so] unjust as to forget the work you are doing and the love you have shown for Him, as you ministered to the saints [i.e., His holy people] and continue to minister [to them].
Hebrews 10:22
we should draw close [to God] with a sincere heart and a fully assured faith, having had our hearts sprinkled from a guilty conscience [See 9:13-14] and having had our bodies washed with clean water [i.e., in our immersion].

Assure

Romans 4:21
and was fully convinced that what He had promised, He was able to carry out.
Romans 8:38
For I am convinced that neither death, nor [the trials of] life, nor [evil] angels, nor [evil] rulers, nor present or future [circumstances], nor [evil] powers,
2 Timothy 1:12
For I am suffering these things [See verse 8] for this reason [i.e., because of being a Gospel preacher]. Yet I am not ashamed because I know whom I have believed in [i.e., Jesus], and I am convinced that He is able to guard what I have entrusted to Him [i.e., Paul's spiritual well-being] until that day [i.e., the day of judgment].
Hebrews 11:13
These people [all] continued to have faith until they died, [even though] they had not obtained [all] the things God had promised, but had [only] seen them and welcomed them from a distance. And they had confessed to being strangers and aliens on earth.