TT #669 · Parashas Ki Seitzei · Seventh Aliyah · Passuk 25:05
When brothers dwell together and one of them dies and has no son, the wife of the dead shall not be outside to a strange man; her husband’s brother shall come upon her and take her to himself as a wife and perform the duty of a husband’s brother for her.
Torah Temimah points to Yevamot 39a.
TT lemma: וּלְקָחָהּ לוֹ לְאִשָּׁה וְיִבְּמָהּ.
מִי שֶׁרְאוּיָה לִלְקוּחִין וְקִדּוּשִׁין תּוֹפְסִין בָּהּ – הִיא זְקוּקָה לְיָבָם.
English: Only a woman who is fit for acquisition and in whom kiddushin can take effect is bound to the yavam.
On the daf / in context: The verse’s language of “taking as a wife” presupposes basic eligibility for marriage.
Derash on eligibility for the marital bond.
A woman ineligible for ordinary kiddushin (e.g., certain forbidden relationships) is not subject to the zikah of yibbum.