The apostle James warned people who did not pay their workers:
“Now, you rich people, weep and cry aloud. There are terrible troubles that will soon be coming to you. Your riches have lost their value. Your beautiful clothes are as if moths had eaten them. Your gold and your silver have become dirty and stained. The dirt and stains will be evidence against you in the judgement. They are like poison that will eat up your bodies as with fire. That is because you have heaped up a lot of riches in these last days. Listen! You have not paid the wages of those who worked in your fields. The money you kept from them cries out to God against you. The Lord of all power has heard the cries of the workers. You have lived on earth in luxury. And you have had all that you wanted. You lived to please yourselves. You have made yourself fat, like animals ready for men to kill. You have accused. And you have caused the death of those who were innocent.”
James 5:1-6
The apostle Paul wrote to Christian slave masters:
“Those of you who are masters must also be fair to your slaves. You must not frighten them by saying that you will hurt them. Remember that you and your slaves have the same master in heaven. God is fair and you are all his slaves. He does not think that masters in this world are more important than their slaves.”
Ephesians 6:9
You can read the whole of Paul’s letter to the Christians at Ephesus: Christian Belief and Behaviour
See also: What does the Bible say about employees?