'Bought' in the Bible

and they sing, as it were, a new song before the throne, and before the four living creatures, and the elders, and no one was able to learn the song except the hundred forty-four thousands, who have been bought from the earth;

these are they who with women were not defiled, for they are virgin; these are they who are following the Lamb whithersoever he may go; these were bought from among men -- a first-fruit to God and to the Lamb --