Deuteronomy 25:9

Then shall his sister-in-law come to him before the sages, and there shall be a shoe upon the foot of the brother-in-law, a heeled sandal whose lachets are tied, the latchets at the opening of the sandal being fastened; and he shall stamp on the ground with his foot; and the woman shall arise and untie the latchet, and draw off the sandal from his foot, and afterward spit before him, as much spittle as may be seen by the sages, and shall answer and say, So is it fit to be done to the man who would not build up the house of his brother.

The Hebrew word unlace also implies “pull off”, as in “pull out the breast” [Lamentations 4: 3].

Our traditional sources inform us [Sifrey on this verse] that the word facing him here has the sense of “in his presence” [and not that she must spit in his face — Translator]. In fact, the most straightforward interpretation is “facing it ” — i.e., facing the shoe. Compare, “written on its face and on its back” [Ezekiel 2: 10].

וחלצה נעלו, in order thereby to acquire the inheritance of his deceased brother, as we know from the situation of Boaz (Ruth 4,7-8) [according to the view of Levi in Baba Metzia 47 that chattels of the party transferring the property, מקנה, are used for that purpose. This is not the halachically accepted view. Ed.]

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.”