Slave:

Person considered property of another and completely under his control. The practice of having slaves began in ancient times.

Abraham, according to his time, had them (Genesis 15: 3.);
Joseph was sold as a servant (literally "slave" Psalm 105: 17.) And Israel was a nation enslaved in Egypt (Dt 16:12; 24:18, 22; etc.).
Slaves were common in Mesopotamia, where they could be bought for about 40 shekels; therefore, many citizens acquired for domestic and agricultural work. In Egypt, however, they were less numerous and mostly had only the rich, but sometimes war veterans, who received them as a reward for their courage.

A slave could acquire it by war (2 Kings 5: 2.) Or purchase (Ex 12:44.), Sometimes as payment of a debt (2 Kings 4: 1; Leviticus 25:39.) ; I could be born as a slave in the house of his master (Genesis 15: 3.), or could be received as an inheritance (Leviticus 25:46.). A Hebrew slave only he could be required to work 6 years (Ex. 21: 2), a law that is not always observed (Jer. 34: 8-11).

When a slave was set free, the slave wife who had given her and the children who were born to him were the property of master (Ex. 21: 2-4). The slave could, if desired, be as such in perpetuity, in which case the master pierce his ear with an awl as a sign of servitude (vs 5, 6).

A servant or slave capable and talented could move to a position of importance (Proverbs 17: 2; Ps. 105: 17-21; Gen. 41: 42-44.).

One owner was punished for killing a slave (Ex. 21: 20), and a slave was to be delivered in certain cases of dismemberment of the body (v 26).

A servant who had escaped not to be forcibly returned to his master (Deut. 23:15). Sometimes a man sold his daughter as a slave (Ex. 21: 7) to become secondary wife or concubine. According to Herodotus, this was a regular practice among the Thracians.

Solomon became slaves to the Canaanites who survived on Earth (1 Kings. 9:21), but not the Israelites (v 22).
Under an ancient Roman law the slave was absolute mercy of his master for life or death. I could not appeal to the civil courts, he could not own property, but was subject to minor whim of its owner. As a result, many suffered a heavy servitude. On one occasion, when a Roman senator was assassinated by a slave, his death was avenged the killing of the 400 that had the family. However, some masters treated their slaves with great consideration (Luke 7: 2.). Christians apparently had owned slaves in Paul (Eph. 6: 5-9). * Onesimus (Phm. 10-16) was a slave who had run away, but who, thanks to the efforts of Paul, had become Rome and had been sent by him back to his master in Colossae.
It advised the Christian slave to not be discouraged by their physical bondage (1 Cor 7: 20-22; 1 Tim 6: 1, 2.).

In view of YHVH Almighty God, the soul of a slave is as precious as a free man (Gal. 3:28).

In the AT recognize and regulate slavery should be understood against the backdrop of the immaturity of the Hebrews and the very low level of heathenism around them.

YHVH Almighty God dealt with generosity to his people in times of their ignorance.

But this raises a question regarding why Christianity did not abolish slavery input.

Jesus commanded:
"Love one another" (John 34-35). (The fulfillment of this commandment gives freedom spiritual and earthly from slavery even in current times).


* The term "slave"  is used in the New Testament mostly in Spiritual sense:

"The sinner is a slave of sin he commits, because they control (John 8:34; Rom 6:17; Gal 4:.. 3; Tit. 3: 3; Rom 6:16; etc...).

"A religion based on ceremonies and legalism is a religion of spiritual slavery (Galatians 4: 9-11, 21-23; 5:. 1-4; etc.).

Paul speaks of himself as a "slave" of Jesus Christ (Rom. 1: 1), not in the sense of slavery but by voluntary and loving choice. Only one who is "slave" of Jesus Christ is truly free (John 8: 34-36; cƒ 1 Cor 7:22; Gal. 5: 1; etc..).

Bible Dictionary