How do sola fide adherents explain The Parable of the Ten Virgins?

In [Matthew 25:1-12](https://www.biblegateway.com/passage/?search=Matthew+25%3A1-12&version=ESV) we read about ten young ladies (a bridal party) eagerly awaiting the arrival of the groom. Five of them run out of oil and have to go buy more, missing the groom's arrival and thus be excluded from the wedding feast. The groom is universally seen as representing Jesus, the women are seen as representing individual believers, and the oil is generally seen as representing God's grace. (See [my analysis](https://hermeneutics.stackexchange.com/a/20227/10092) on the parable and especially the symbolism of the oil.) A surface reading would seem to indicate that all the women were nominally believers in Jesus, but someone of them did not properly prepare for his arrival (i.e. for their death or Jesus' Second Coming). This would suggest that there is more to salvation than faith alone - an aspect that can be "bought". How do *sola fide* adherents explain this passage? A good answer should cite published commentary by notable advocates of salvation by faith alone.