Sackcloth

"Cloth made of black goats' hair, coarse, rough, and thick, used" "for sacks, and also worn by mourners (Gen. 37:34; 42:25; 2 Sam." "3:31; Esther 4:1, 2; Ps. 30:11, etc.), and as a sign of" repentance (Matt. 11:21). It was put upon animals by the people of Nineveh (Jonah 3:8).

Jonah 3 Hosea's channel https://youtu.be/T8ToqeP4fv8

King James Version

3 And the word of the Lord came unto Jonah the second time, saying,
2 Arise, go unto Nineveh, that great city, and preach unto it the preaching that I bid thee.
3 So Jonah arose, and went unto Nineveh, according to the word of the Lord. Now Nineveh was an exceeding great city of three days' journey.
4 And Jonah began to enter into the city a day's journey, and he cried, and said, Yet forty days, and Nineveh shall be overthrown.
5 So the people of Nineveh believed God, and proclaimed a fast, and put on sackcloth, from the greatest of them even to the least of them.
6 For word came unto the king of Nineveh, and he arose from his throne, and he laid his robe from him, and covered him with sackcloth, and sat in ashes.
7 And he caused it to be proclaimed and published through Nineveh by the decree of the king and his nobles, saying, Let neither man nor beast, herd nor flock, taste any thing: let them not feed, nor drink water:
8 But let man and beast be covered with sackcloth, and cry mightily unto God: yea, let them turn every one from his evil way, and from the violence that is in their hands.
9 Who can tell if God will turn and repent, and turn away from his fierce anger, that we perish not?
10 And God saw their works, that they turned from their evil way; and God repented of the evil, that he had said that he would do unto them; and he did it not.


Bible Verses About Repentance

Bible verses related to Repentance from the King James Version (KJV)
Acts 3:19 - Repent ye therefore, and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord;

2 Chronicles 7:14 - If my people, which are called by my name, shall humble themselves, and pray, and seek my face, and turn from their wicked ways; then will I hear from heaven, and will forgive their sin, and will heal their land.

1 John 1:9 - If we confess our sins, he is faithful and just to forgive us [our] sins, and to cleanse us from all unrighteousness.

2 Peter 3:9 - The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.

Luke 13:3 - I tell you, Nay: but, except ye repent, ye shall all likewise perish.

Acts 17:30 - And the times of this ignorance God winked at; but now commandeth all men every where to repent:

Acts 2:38 - Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.

Ezekiel 18:21-23 - But if the wicked will turn from all his sins that he hath committed, and keep all my statutes, and do that which is lawful and right, he shall surely live, he shall not die.   

Revelation 2:5 - Remember therefore from whence thou art fallen, and repent, and do the first works; or else I will come unto thee quickly, and will remove thy candlestick out of his place, except thou repent.

Proverbs 28:13 - He that covereth his sins shall not prosper: but whoso confesseth and forsaketh [them] shall have mercy.

Matthew 4:17 - From that time Jesus began to preach, and to say, Repent: for the kingdom of heaven is at hand.

Romans 2:4 - Or despisest thou the riches of his goodness and forbearance and longsuffering; not knowing that the goodness of God leadeth thee to repentance?