Deut. 23:15, “You shall not hand over to his master a slave who has escaped from his master to you.”

The status of the slave in biblical context as property (Exodus 21:21) is not the same kind as chattel slavery where an individual was considered property as was a goat, or a garment.  In biblical times, mere ‘property’ was to be returned.

• Exodus 22:26, “If you ever take your neighbor’s cloak as a pledge, you are to return it to him before the sun sets,”
• Exodus 23:4, “If you meet your enemy’s ox or his donkey wandering away, you shall surely return it to him.”

But, escaped slaves were not to be returned (Deut. 23:15). If the slave was property in the chattel sense, then it would make no sense for the Scriptures to say not to return an escaped slave to his master. Therefore, the sense in which a person was considered property in the biblical context is not the same thing as property in chattel slavery.

Furthermore, slaves had rights. The mere property does not have rights. Please consider the following:

1.  A slave could voluntarily decide to stay as a slave (Deut. 15:16-17).
2. When a slave was freed, he was to receive gifts that enabled him to survive economically (Deut. 15:14).
3. A Hebrew slave could become free after six years of service (Exodus 21:2; Deut. 15:12), released during the year of Jubilee (Lev. 25), by marriage of the master’s son or if refused was then set free (Exodus 21:7-11), due to injury of eye or tooth (Exodus 21:26-27), and by purchasing his own freedom (Lev. 25:47).
4. An escaped slave was not to be returned as was property (Deut. 23:15–16).
5. ​The slave was a member of the master’s household (Lev. 22:11) and was required to rest on the Sabbath (Exodus 20:10; Deut. 5:14).  A slave could inherit property (Genesis 15:2-3), be in control of entire households (Gen. 24:2), and were sometimes trusted advisors (1 Sam. 9:5-10).
6. Treatment of slaves was not to be severe (Lev. 25:43, 53).
7. A master who punished his slave who then died, was to be punished himself possibly with death (Exodus 21:20). Slaves were considered as a form of property (Lev 25:46; Ex 21:32; Lev 25:39-42) but not in the strictest sense, since escaped slaves were not to be returned as was property (Deut. 23:15–16).
8. Kidnapping someone to make them a slave was prohibited (Amos 1:6) and was punishable by death (Deut. 24:7; Exod. 21:16).
   • https://carm.org/slavery-in-the-bible-is-not-the-same-as-the-chattel-slavery-of-america

Conclusion: A Slave Was Not Seen as Mere Property

In biblical times, a slave was not considered mere property to be traded and mistreated, etc. The wrongful death of a slave was met with execution (Exodus 21:12). An injury to an eye or tooth resulted in his freedom (Exodus 21:26). And, if the slave had escaped from his master, he was not to be returned (Exodus 23:15) as was property (Exodus 22:26; 23:4)? Finally, mere property does not have rights. But slaves in the Old Testament could inherit property (Genesis 15:2-3), be in control of households (Genesis 24:2), and were sometimes trusted advisors (1 Sam. 9:5-10). Therefore, slavery of the Old Testament was not chattel slavery and the fact that escaped slaves were not to be returned, is proof that they were considered as people, not mere property.