TT #655 · 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 / Sifrei.
TT lemma: הַחוּצָה.
הַחוּצָה – לְרַבּוֹת אֶת הָאֲרוּסָה.
English: “Outside” — this includes the betrothed (arusah).
On the daf / in context: Even a woman only betrothed (not yet fully married) to the deceased falls under the zikah of yibbum and requires chalitzah or yibbum.
Ribbui from the word “outside.”
An arusah (betrothed woman) of the deceased is subject to yibbum and chalitzah.