Source
Matthew 20
20 For the kingdom of heaven is like a man, a householder, who went out in the morning to hire workers for his vineyard.
2 And having agreed with the workers for a denarius a day, he sent them into his vineyard.
3 Leaving about the third hour of the day, he saw others who were in the square unoccupied;
4 And he said to them, "You also go into my vineyard, and whatever is right I will give you." And they were.
5 He went out again around the sixth and ninth hours, and did the same.
6 And going out about the eleventh hour, he found others who were unoccupied; and he said to them: Why are you here all day unoccupied?
7 They said to him: Because no one has hired us. He said to them, "You also go into the vineyard, and whatever is right you will receive."
8 When evening came, the lord of the vineyard said to his steward: Call the workers and pay them their wages, beginning from the last to the first.
9 And when those who had come about the eleventh hour came, they each received a denarius.
10 When the first ones also came, they thought that they would receive more; but they also each received a denarius ...
(RVR1960)
The parable has its origin in the disciples' attitude towards service and rewards. Although rewards will be received, Jesus rejects the desire to serve for rewards rather than love.
It is important to note that a denarius was the wage promised for a whole day of work and that the first tasks began at 6:00 am. however the reference in this verse is to 9.am.
Verse 8 "beginning from the last" refers to the problem that arises in the parable due to the order to pay first to the last. This arouses the expectations of those who arrived before the vineyard.
His complaint was that those who had contributed less received equal pay.
This parable affirms that God is absolutely sovereign and generous in his gifts because those who serve him can trust his grace because he does not act like any of us.
Jesus motivates his disciples to live in justice since the fruits of an individual's life and work are a better indicator of personal motivations than appearances or statements and in his absolute sovereignty God does as he wants and to whom he wants.