Matthew Poole and continuators on Song of Solomon 6:9

9 My dove, my undefiled is but one ; she is the only one of her mother , she is the choice one of her that bare her: the daughters saw her, and blessed her; yea, the queen and the concubines, and they praised her .

The only beloved of my Soul, my only Spouse, in comparison of whom I despise all others.

Of Ierusalem above, which is the Mother of us all, Gal. 4. 26. Or, if this seem to confound the Mother & Daughter, the words may be thus rendred, she is as the only one of her mother, i. e. she is as dear & pretious to me as onely Children use to be to their Parents, and especially to their Mothers. So there is only a defect of the note of similitude, which is frequently understood, as hath been formerly noted and proved by undeniable instances.

Called Virgins, v. 8.

As more beautiful and worthy than themselves, which was so evident that they were forced to confess it.