7 Now this was the custom in former time in Israel concerning redeeming and concerning exchanging, to confirm all things: a man took off his sandal, and gave it to his neighbor; and this was the way of formalizing transactions in Israel.
Ruth 4:7 Cross References - WEB
Deuteronomy 25:7-10
7 If the man doesn’t want to take his brother’s wife, then his brother’s wife shall go up to the gate to the elders, and say, “My husband’s brother refuses to raise up to his brother a name in Israel. He will not perform the duty of a husband’s brother to me.”
8 Then the elders of his city shall call him, and speak to him. If he stands and says, “I don’t want to take her,”
9 then his brother’s wife shall come to him in the presence of the elders, and loose his sandal from off his foot, and spit in his face. She shall answer and say, “So shall it be done to the man who does not build up his brother’s house.”
10 His name shall be called in Israel, “The house of him who had his sandal removed.”