(1) And Boaz went up to the gate, and sat down there. And behold, he that had the right of redemption, of whom Boaz had spoken, came by. And he said, Thou, such a one, turn aside, sit down here. And he turned aside and sat down. (2) And he took ten men of the elders of the city, and said, Sit down here. And they sat down. (3) And he said to him that had the right of redemption: Naomi, who is come back out of the country of Moab, sells the allotment that was our brother Elimelech's. (4) And I thought I would apprise thee of it and say, Buy [it] in the presence of the inhabitants, and in the presence of the elders of my people. If thou wilt redeem [it], redeem; but if thou wilt not redeem, tell me, that I may know; for there is none to redeem besides thee; and I am after thee. And he said, I will redeem [it]. (5) And Boaz said, On the day thou buyest the field of the hand of Naomi, thou must buy [it] also of Ruth the Moabitess, the wife of the dead, to raise up the name of the dead upon his inheritance. (6) And he that had the right of redemption said, I cannot redeem [it] for myself, lest I mar mine own inheritance. Redeem thou for thyself what I should redeem, for I cannot redeem [it]. (7) Now this [was the custom] in former time in Israel concerning redemption and concerning exchange, to confirm the whole matter: a man drew off his sandal, and gave it to his neighbour, and this was the [mode of] attestation in Israel. (8) And he that had the right of redemption said to Boaz, Buy for thyself; and he drew off his sandal. (9) And Boaz said to the elders and all the people, Ye are witnesses this day, that I have bought all that was Elimelech's, and all that was Chilion's and Mahlon's, of the hand of Naomi; (10) moreover Ruth the Moabitess, the wife of Mahlon, have I purchased to be my wife, to raise up the name of the dead upon his inheritance, that the name of the dead be not cut off from among his brethren and from the gate of his place: ye are witnesses this day. (11) And all the people that were in the gate and the elders said, [We are] witnesses. Jehovah make the woman that cometh into thy house like Rachel and like Leah, which two did build the house of Israel; and acquire power in Ephratah, and make thyself a name in Bethlehem;
This scene is typical of how most cultures, not only the Hebrews, have understood the idea of witnessing. These ten elders of the city—and, if we read between the lines in verse 11, all the people who were drawn to this event that Boaz set up—observed the negotiations and the transaction of the sandal between Boaz and the unnamed near kinsman. If there were ever a need for proof that Boaz had indeed jumped through all the legal hoops through which he needed to jump to procure the land of Elimelech and the hand of Ruth, he had ten expert, irreproachable witnesses from among the elders of the people. In fact, he had probably dozens more who had seen all this take place because it most likely took place at the gate of the city.
So, many people were able to see what had transpired and could testify that everything had been done above-board. In a way, these people functioned like today's notaries who witness a legal transaction, put their seal on a document, and sign it, verifying that, "Yes, I indeed saw this transaction take place, legally and above-board, etc." This is how witnessing is done, and this is what many, if not most, of the occurrences of the Old Testament Hebrew words for "witness," 'ed and 'ud (the noun and the verb, respectively), connote.
What happened here in Ruth 4 is very interesting in the fact that Boaz is a type of Christ. Boaz here chooses ten elders—Jews—respected men of the town to witness what he did. Remember, since this took place in Bethlehem, these Jews were probably kin of David. In fact, Boaz himself was David's great-grandfather, but these people were all one big extended family, the family of Judah. Boaz took ten of them, ten men whose eyewitness testimony could not be gainsaid in any way, and these men then witnessed his redemption of the land and Ruth.
What is interesting is that Jesus did exactly the same thing, except that He chose twelve men of Judah from Galilee. They would do the same for Him, telling all who would hear that He had indeed redeemed His people. Luke 24:44-49 shows that this is exactly what He did. While the normal, legal idea of witnessing appears in the New Testament, Jesus makes use of it to confirm the facts of His life and death to the whole world through His witnesses, the apostles.
— Richard T. Ritenbaugh