The Shach asks a question on the Rema in the Shulchan Aruch . The Gra answers it in one way and Rav Shmuel Rozovski of Ponovitch answers it differently based on a Tosphot in Ketuboth page 20. The subject in short is this. The Shulchan Aruch and Rema write that witnesses need to testify verbally, not by writing. But to validate a document, the Rema says one can testify by writing. And yet later on when the Shulchan Aruch writes if one is a witness, and then became unable to speak , he cannot testify as for the validity of his signature (even by writing). And the Rema does not disagree there. Why? The answer of Rav Shmuel Rozovski is based on an opinion in Tosphot. To Tosphot, a document that is written against the will or consent of the borrower does not have the category of a valid document. (Another opinion in Tosphot is that a document with only one witness does not have the category of a valid document.) Rav Rozovski says the Rema holds with the first opinion. A witness that is only validating his signature does not need to validate it verbally because presumably the borrowers is objecting. Therefore, the document does not have the category of a document, and so the witnesses do not need to speak verbally. Only the actual witness on a document needs to speak. But in the case of one witness on a document that became unable to speak, there the document does have the category of a document, and so it is not valid for him to testify by writing. The problems with these answers are theses. Witnesses on a document do not need to speak. Only testimony needs to be spoken, not signatures on a document. This is a general question on the idea of applying that fact that testimony needs to be verbal and applying it to signatures.] Next question: There is a difference between writing a document and testifying as for its validity. Rav Shmuel says the document is not a document if written against the will of the borrower, but in our case for all we know the document was written with the consent of the borrower. All the witnesses are doing now is validating their signatures. (So the document is presumably valid and the witnesses should testify only verbally.) But Rav Shmuel could answer that in our case, it seems that the borrower is claiming the document is invalid for some reason. Maybe the reason is that he did not agree to its being written? And the witness is not saying it was written with his consent. All the witnesses say is that there was a loan and says nothing about how the שטר was written. The answer of the Gra is short, but Rav Shach explains it thus. The Rema holds like the Rivash [Rav Izhak ben Sheshet] that a witness can validate his signature by writing. This is coming like Rav Kahana in Gitin 71 side a who says a deaf person can write, ‘’Write and give a divorce to my wife, and it is valid. But a person who cannot speak cannot give testimony because not being able to speak is a defect of the body. So, to testify as for the validity of one’s signature we need valid witnesses, and if we have that then they can write that the signature is valid. But one who cannot speak is not a valid witness at all.] The problem I see is that Rav Kahana says nothing about validating one’s signature. He only speaks about a deaf person giving a command in writing to divorce his wife. I might mention that even though R. Yochanan disagrees with Rav Kahana still there is R. Isaac on page 71 side b who explains the Mishna there to be in accord with Rav Kahana. {So we can see why the Rivash [Issac ben Sheshet] decided like Rav Kahana against R. Yochanan.} ----------------------------------------------------------------------------------------------------------The ש''ך asks a question on the רמ''א in the שלחן ערוך. The גר''א answers it in one way and רב שמואל רוזובסקי answers it differently based on a תוספות בכתובות דף כ'. The subject in short is this. The שלחן ערוך and רמ''א write that witnesses need to testify verbally, not by writing. But to validate a document, the רמ''א says one can testify by writing. And yet later on when the שלחן ערוך סימן מ''ו ס''ק ל''ו writes if one is a witness, and then became unable to speak, he cannot testify as for the validity of his signature (even by writing). And the רמ''א does not disagree there. Why? The answer of רב שמואל רוזובסקי is based on an opinion in תוספות. To תוספות, a document that is written against the will or consent of the borrower does not have the category of a valid document. (Another opinion in תוספות is that a document with only one witness does not have the category of a valid document.) רב שמואל רוזובסקי says the רמ''א holds with the first opinion. A witness that is only validating his signature does not need to validate it verbally because presumably the borrowers is objecting. Therefore, the document does not have the category of a document, and so the witnesses do not need to speak verbally. Only the actual witness on a document needs to speak. But in the case of one witness on a document that became unable to speak, there the document does have the category of a document, and so it is not valid for him to testify by writing. The problems with these answers are theses. Witnesses on a document do not need to speak. Only testimony needs to be spoken, not signatures on a document. This is a general question on the idea of applying that fact that testimony needs to be verbal and applying it to signatures.] Next question: There is a difference between writing a document and testifying as for its validity. רב שמואל רוזובסקי says the document is not a document if written against the will of the borrower, but in our case מסתברthe document was written with the consent of the borrower. All the witnesses are doing now is validating their signatures. (So, the document is presumably valid and the witnesses should testify only verbally.) But רב שמואל could answer that in our case, it seems that the borrower is claiming the document is invalid for some reason. Maybe the reason is that he did not agree to its being written? And the witness is not saying it was written with his consent. All the witnesses say is that there was a loan and says nothing about how the שטר was written. The answer of the גר''א is short, but רב שך explains it thus. The רמ''א holds like the (ריב’’ש) רב יצחק בן ששת that a witness can validate his signature by writing. This is coming like רב כהנא in גיטין דף ע''א side a who says a deaf person can write, ‘’Write and give a divorce to my wife, and it is valid. But a person who cannot speak cannot give testimony because not being able to speak is a defect of the body. So, to testify as for the validity of one’s signature we need valid witnesses, and if we have that, then they can write that the signature is valid. But one who cannot speak is not a valid witness at all.] The problem I see is that רב כהנא says nothing about validating one’s signature. He only speaks about a deaf person giving a command in writing to divorce his wife. I might mention that even though ר’ יוחנן disagrees with רב כהנא still there is ר' יצחק on דף ע''א who explains the משנה there to be in accord with רב כהנא. {So, we can see why the ריב''ש יצחק בן ששת decided like רב כהנא against ר’ יוחנן.}