וְנִגְּשָׁ֨ה יְבִמְתּ֣וֹ אֵלָיו֮ לְעֵינֵ֣י הַזְּקֵנִים֒ וְחָלְצָ֤ה נַעֲלוֹ֙ מֵעַ֣ל רַגְל֔וֹ וְיָרְקָ֖ה בְּפָנָ֑יו וְעָֽנְתָה֙ וְאָ֣מְרָ֔ה כָּ֚כָה יֵעָשֶׂ֣ה לָאִ֔ישׁ אֲשֶׁ֥ר לֹא־יִבְנֶ֖ה אֶת־בֵּ֥ית אָחִֽיו
allora sarà suo fratello'la moglie si avvicina a lui alla presenza degli anziani, si toglie la scarpa dal piede e gli sputa in faccia; e lei risponderà e dirà:'Così sarà fatto all'uomo che non costruisce suo fratello'casa di s.'
Rashi on Deuteronomy
וירקה בפניו THEN SHE SHALL SPIT BEFORE HIS FACE — on the ground (not in his face) (Yevamot 106b).
Sforno on Deuteronomy
ככה יעשה לאיש אשר לא יבנה את בית אחיו, he deserves this public embarrassment seeing he had refused to restore the house his deceased brother had begun to build when he betrothed his (now) widow. This reminds us of the statement in Shabbat 118 by Rabbi Yossi who did not refer to his wife as אשתי, “my wife,” but as ביתי, “my house.”
Or HaChaim on Deuteronomy
וענתה ואמרה ככה יעשה לאיש, "and she will say in reply: "so shall be done to any man, etc." The reason the Torah employs the term עניה, "reply," is because it is in answer to her brother-in-law who had refused to marry her.