"ve'Chi Sechdal Lindor ? ". What is this Pasuk coming to teach us?
Rashi (in Yevamos, 109b): It teaches us, by implication, that if one does declare a Neder, he has sinned (and is called a Rasha ? Nedarim, 22a). 1
Ramban: It teaches us that, in spite of the great reward that the Torah promises those who bring Korbanos, 2 and the fact that Nedarim are a means of encouraging one to attain that reward, 3 it is preferable not to make Nedarim. 4
Nedarim, ibid.: Even if he fulfills it, which we learn via a Gezeirah Shavah "Sechdal" "Sham Resha'im Chadlu Rogez", in Iyov, 3:15. See also Torah Temimah, citing Nedarim, 22a and note 122.
Ramban: See for example, Tehilim, 66:15, 13 and Vayikra, 1:4.
Ramban: See Tehilim, 116:18.
Ramban: As the Pasuk writes in Koheles, 5:3 & 4. Because of the inherent danger of making a Neder and delaying its implementation, resulting in punishment. Bear in mind that, even if one does not bring a [voluntary] Korban during his entire lifetime, he has not sinned (Moreover, if he wants to bring a Korban, he has the option of bringing it as a Nedavah, direct to the Beis-Hamikdash without making a Neder.
