Well, now that you mention "penitence", here are some examples from the Bible:
Luke 13:3
No, I say to you: but unless you shall do penance, you shall all likewise perish.
{This is a solemn promise of Christ to all of us. Unless we do penance, we will “perish.”}
Job 42:6
Therefore I reprehend myself, and do penance in dust and ashes.
Ecclesiasticus 2:22
If we do not penance, we shall fall into the hands of the Lord, and not into the hands of men.
{If we don’t experience discipline in this life, we shall experience it in the next.}
Jeremiah 31:19
For after thou didst convert me, I did penance: and after thou didst shew unto me, I struck my thigh: I am confounded and ashamed, because I have borne the reproach of my youth.
{Notice here, that penance comes after conversion.}
Lamentations 2:14
Thy prophets have seen false and foolish things for thee: and they have not laid open thy iniquity, to excite thee to penance: but they have seen for thee false revelations and banishments.
{Here the spiritual leaders of Israel have wrongly induced the people to follow after false revelations or apparitions. Instead, they should have led the people to penance. Incidentally, Saint Francis is the perfect example of the right leader. He doesn’t appeal to apparitions or even to his stigmata. He appeals to the power of prayer, fasting, and penance.}
Ezekiel 18:21
But if the wicked do penance for all his sins which he hath committed, and keep all my commandments, and do judgment, and justice, living he shall live, and shall not die.
{This is the great promise for Lent. If we humble ourselves and live sacrificially, we will have life. God is merciful and loving and He desires our transformation into the image of Christ His Son.}
Matthew 3:8
Bring forth therefore fruit worthy of penance.
{Here we find that true repentance requires fruit – it requires outward acts that conform to the inward reality.}
Matthew 11:20
Then began he to upbraid the cities wherein were done the most of his miracles, for that they had not done penance.
{This is a sobering verse. Christ doesn’t work miracles where the people don’t repent. Divine power is restricted by human pride.}
Romans 2:4
Or despisest thou the riches of his goodness, and patience, and longsuffering? Knowest thou not, that the benignity of God leadeth thee to penance?
{The love, mercy, and benignity of God brings us to a true repentance. Notice that being mean and hateful does not bring others to penance.}
Apocalypse 2:5
Be mindful therefore from whence thou art fallen: and do penance, and do the first works. Or else I come to thee, and will move thy candlestick out of its place, except thou do penance.
{Here “do penance” and “do the first works” are paired together. Penance has an outward dimension, because sin also has an outward dimension. The horrifying truth is that Christ will snuff out the Church of any region if they don’t live a life of penitence.}