TT #754 · Parashas Ki Seitzei · Seventh Aliyah · Passuk 25:09
Then his yevamah shall approach him in the presence of the elders, and draw his shoe off his foot, and spit in his face, and respond and say: “Thus shall be done to the man who will not build up his brother’s house.”
Torah Temimah points to Yevamot 24a.
TT lemma: אֲשֶׁר לֹא יִבְנֶה אֶת בֵּית אָחִיו.
אֲשֶׁר לֹא יִבְנֶה – וְלֹא אֲשֶׁר לֹא בָּנָה; אִם כָּנַס וּגֵרֵשׁ – אֵין חוֹלְצִין.
English: “Who will not build” — and not “who has not built”; if he took her in yibbum and then divorced her, chalitzah is not performed.
On the daf / in context: Once the house has been built (yibbum performed), subsequent divorce does not reopen the possibility of chalitzah.
Derash from the future tense.
If yibbum was performed and the marriage later ended in divorce, no chalitzah is required or possible.