From the Christian Bible, which endorses slavery... There are passages in the Bible, in both the old and the new testaments, which condone slavery...
I've thought more about your use of "condone" only to come back and find that you originally used "endorse" instead. That's the way I took it, but there are other possibilities. The nuances of our language make it flexible, but that sometimes hinders communication.
Dictionary(OSX) gives two meanings. Condone in one sense can be accept/allow. Certainly, scripture encourages slaves in that time to accept their circumstances*, for they were powerless to change them. I don't want to get deeply into the power thing here... free will, etc. But "allow" implies the ability to put a stop to something that is within one's control. Perhaps that applies, but I'd be more inclined to use "tolerate" instead, in that no punishment was meted out for slave ownership. Free will again...
Condone in another sense can be approve/sanction which gets closer to the concept of endorsement. To that I say emphatically, scripture does no such thing, certainly not in the New Testament, which is what my Christian faith is based on. I'm not as certain about the Old Testament, but I don't recall ever running across such a statement.
For your contention to be correct, the value judgment must be in the text, not a conclusion drawn from your own moral standards, or those of modern society.
Interestingly, dictionary.com gives this meaning to condone: to give tacit approval to
*Elsewhere, scripture encourages everyone to be "content in all circumstances". Pretty good advice, perhaps dependent on one's definition of "content".
