i have many times
hebrews is about returning to the law, which states salvation can be lost and a person can fall away, requiring sacrifice to be given for restoration
the author is making a point, IF it is possible one could fall away, they could NEVER BE RENEWED, and even declaring it can be lost puts Christ to shame, as he would have to be crucified again,
the verses that follow, prove this point, the earth drinks the rain, brings forth herbs usefull for those who cultivate it (we call this fruit of the spirit, gold silver precious stone) but if it bears thorns and thistles it is reflected (wood hay and straw) and near to being cursed, whose end is to be burned (but he himself will be saved even as though through ie, the fruit of his labor will be burned, as wood hay and straw, but he himself, near to being cursed, will be saved.