Then God saw their works, that they turned from their evil way; and God relented from the disaster that He had said He would bring upon them, and He did not do it. ~ Jonah 3:10

Some among the Free grace advocates like to point to Jonah 3:10 and argue that turning from sin is a work, and since we are not saved by works, repentance has no part in our saving faith. This logic is very flawed because we find that the New Testament speaks of faith as a work as well.

Then said they unto him, What shall we do, that we might work the works of God? Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent. ~ John 6:29

Remembering without ceasing your work of faith, and labour of love, and patience of hope in our Lord Jesus Christ, in the sight of God and our Father … ~ 1 Thessalonians 1:3

Wherefore also we pray always for you, that our God would count you worthy of this calling, and fulfil all the good pleasure of his goodness, and the work of faith with power… ~ 2 Thessalonians 1:11

Furthermore, in the gospels, Jesus references the repentance of Nineveh to whom Jonah preached as a warning against those who refused to repent and believe the gospel during his generation.

The men of Nineveh shall rise in judgment with this generation, and shall condemn it: because they repented at the preaching of Jonas; and, behold, a greater than Jonas is here. ~ Matthew 12:41 (See also Luke 11:32)

Ironically, Matthew 12:41 & Luke 11:32 would be one of the verses the FG adherents would claim means a change of mind only because those texts do not explicitly mention sin, although sin is the context of the repentance. 

But when the Pharisees heard it, they said, This fellow doth not cast out devils, but by Beelzebub the prince of the devils. And Jesus knew their thoughts, and said unto them, Every kingdom divided against itself is brought to desolation; and every city or house divided against itself shall not stand: And if Satan cast out Satan, he is divided against himself; how shall then his kingdom stand? And if I by Beelzebub cast out devils, by whom do your children cast them out? therefore they shall be your judges. But if I cast out devils by the Spirit of God, then the kingdom of God is come unto you. Or else how can one enter into a strong man’s house, and spoil his goods, except he first bind the strong man? and then he will spoil his house. He that is not with me is against me; and he that gathereth not with me scattereth abroad. Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men. And whosoever speaketh a word against the Son of man, it shall be forgiven him: but whosoever speaketh against the Holy Ghost, it shall not be forgiven him, neither in this world, neither in the world to come. Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is known by his fruit. O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh. A good man out of the good treasure of the heart bringeth forth good things: and an evil man out of the evil treasure bringeth forth evil things. But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment. For by thy words thou shalt be justified, and by thy words thou shalt be condemned. Then certain of the scribes and of the Pharisees answered, saying, Master, we would see a sign from thee. But he answered and said unto them, An evil and adulterous generation seeketh after a sign; and there shall no sign be given to it, but the sign of the prophet Jonas: For as Jonas was three days and three nights in the whale’s belly; so shall the Son of man be three days and three nights in the heart of the earth. The men of Nineveh shall rise in judgment with this generation, and shall condemn it: because they repented at the preaching of Jonas; and, behold, a greater than Jonas is here. The queen of the south shall rise up in the judgment with this generation, and shall condemn it: for she came from the uttermost parts of the earth to hear the wisdom of Solomon; and, behold, a greater than Solomon is here. When the unclean spirit is gone out of a man, he walketh through dry places, seeking rest, and findeth none. Then he saith, I will return into my house from whence I came out; and when he is come, he findeth it empty, swept, and garnished. Then goeth he, and taketh with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first. Even so shall it be also unto this wicked generation. ~ Matthew 12:24-45

From the context above we can see that the repentance of Nineveh, to which Jesus holds his generation accountable, parallels their sinful and wicked ways. Jesus wasn’t just speaking about making a quick decision to believe he was the Messiah, he was comforting the manner of people they were. Thus he calls them an evil and adulterous generation, and says that the men of Nineveh shall rise in judgment with this generation, and shall condemn it: because they repented at the preaching of Jonas; and, behold, a greater than Jonas is here.