1)
What is the meaning of "Lefalei Neder"?
1.
Rashi: It means that a Neder and a Nedavah take effect only if they are verbalized, but not via thoughts alone.
2.
Ramban: Refer to 22:18:152:1.
2)
What re the connotations of "Kol Mum Lo Yih'yeh bo"?
1.
Rashi (in Mo'ed Katan, 13a): It is a La'av against making a blemish on Kodshim.
