What is this Pasuk coming to teach us?
Rashi (in Yevamos, 109b): It implies that if one does declare a Neder, he has sinned. 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, 77b: And he is called a siiner - even if he keeps it. 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.
Because of the inherent danger of making a Neder and delaying its implementation, resulting in punishment. Ramban: Since, 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.
