What is the significance of "Lehara Oh Leheitiv"?
Rashi: It means that Reuven makes a Shevu'ah to do good or to harm himself. 1
He swears that he will eat (or sleep) and he doesn't or that he will fast and he doesn't (Rashi, Shevu'os, 25a).
What does "le'Chol asher Yevatei" come to include?
Rashi: It comes to include a Shevu'ah regarding the past. 1
He swears that he ate, and really he didn't, or that he didn't, and really he did (Shevu'os 26a).
What is the law of someone who swears falsely to gain money?
Rashi: He is not included in the current Din (of Oleh ve'Yored), but is subject to an Asham. 1
See Pesukim 24, 25.
What are the implications of the word "bi'Sefasayim"?
Rashi, Targum Onkelos and Targum Yonasan: It implies that a Shevu'ah must be verbalized in order to be effective.