not about taking slaves, but owning them ....
Leviticus 25:44-46New International Version (NIV)
44 “‘Your male and female slaves are to come from the nations around you; from them you may buy slaves. 45 You may also buy some of the temporary residents living among you and members of their clans born in your country, and they will become your property. 46 You can bequeath them to your children as inherited property and can make them slaves for life, but you must not rule over your fellow Israelites ruthlessly.
there are sections about selling your - younger than 12 - daughter
... treatment of slaves, 7th yr freeing of all slaves and giving them, livestock and wine when you release them
http://en.wikipedia.org/wiki/The_Bible_and_slavery
unfortunately any search for Bible and Slavery - the 1st 5 pages are atheists and Christ haters - so one must dig through the chaff
although in 1 Samuel 15:13 - Samuel denounces Saul, because he was supposed to kill the Amalekites, instead bringing back slaves, live stock ... etc
18and the LORD sent you on a mission, and said, 'Go and utterly destroy the sinners, the Amalekites, and fight against them until they are exterminated.'…
19"Why then did you not obey the voice of the LORD, but rushed upon the spoil and did what was evil in the sight of the LORD?"…