When thou goest forth to war against thine enemies, and the LORD thy God hath delivered them into thine hands, and thou hast taken them captive, And seest among the captives a beautiful woman, and hast a desire unto her, that thou wouldest have her to thy wife; Then thou shalt bring her home to thine house; and she shall shave her head, and pare her nails; And she shall put the raiment of her captivity from off her, and shall remain in thine house, and bewail her father and her mother a full month: and after that thou shalt go in unto her, and be her husband, and she shall be thy wife. (Deut. 21.10-13)
Origen, Hom. Lev. VII.6, quoted by Henri de Lubac, Medieval Exegesis, Vol. 1, p. 213:
...I too have often gone forth to war against my enemies, and I have found among my spoils a beautiful woman. For even among our enemies we find things that are good and proper. If, therefore, we read wise and knowledgeable words in one of them, we must purify them, we must remove and cut away everything in this knowledge that is deadly and vain. This is just like the hair and nails of this woman who was taken when the enemy was plundered. Thus we shall make her our wife, when she no longer has anything that has the appearance of infidelity, anything that smacks of death on her head or on her hands, so that she no longer bears anything impure or deathful either in her sentiments or in her actions. For the women of our enemies have no purity about them, seeing that there is no wisdom in them that is not mingled with some impurity...As for ourselves, we who are engaged in a spiritual war and who, to destroy the power of the enemy, use not carnal arms, but the power of God, if we find a beautiful woman in the camp of our adversary, that is to say, some rational discipline, in that case we shall purify her, as has just been recounted.
Richard Sibbes, A Christian's Portion; or, The Christian's Charter, in Works, Vol. 4, p. 18:
Again, 'all things are ours.' Therefore truth, wheresoever we find it, is ours. We may read [a] heathen author. Truth comes from God, wheresoever we find it, and it is ours, it is the church's. We may take it from them as a just possession. Those truths they have, there may be good use of those truths; but we must not use them for ostentation. For that is to do as the Israelites; when they had gotten treasure out of Egypt, they made a calf, an idol of them. So we must not make an idol of these things. But truth, wheresoever we find it, is the church's. Therefore with a good conscience we may make use of any human author. I thought good to touch this, because some make a scruple of it.