What is "v'Sham'ah Kol Alah" referring to?
Rashi: It refers to someone who is asked by a litigant to swear that, if he is able to testify on his behalf, he will do so.
What sort of testimony is the Pasuk referring to?
Ramban: It is referring to testimony that is to the advantage of the litigant who is making him swear.
What does "v'Hu Eid, O Ra'ah O Yada" mean?
Ramban #1 (citing Shevu'os, 33b): Seeing without knowing - Where Reuven claims that he counted out to Shimon in front of witnesses, and, when Shimon denies it, he calls the witnesses to come and testify. Knowing without seeing - Where Reuven claims that Shimon admitted to him that he owed him money in front of witnesses, and, when Shimon denies it, he calls the witnesses.
Ramban #2: It means that he is a witness - inasmuch as he either saw the transaction or that he knows about it (because the other litigant admitted it in his presence).
Targum Yonasan: It means that either he himself is a witness, or he saw somebody transgressing an oath or he knows of somebody who transgressed an oath - and declines to inform the Beis-Din. 1
See Na'ar Yonasan.
Why does the Torah omit the phrase "v'Ne'elam Mimenu", that appears in the cases that follow?
Rashi (Shabbos, 68b) and Ramban: Because in this particular case, he is subject to a Korban even be'Meizid. 1
Ramban, Moshav Zekenim: Or b'Shogeg about the Isur to swear falsely, if he remembered the testimony. However, if he forgot the testimony he is exempt.
Why does the Torah omit "bi'Shegagah" from Shevu'as ha'Edus and Shevu'as Bituy? It is in all the other Parshiyos!
Da'as Zekenim: This teaches that the punishment for Shevu'ah is great. Shogeg is considered like Mezid
Why is there a Vov in "Lo"?
Moshav Zekenim: We read "Lo" like with a Vov