The very existence of Kol Nidre suggests that the rabbis did not look very favorably on the practice of vowing. The Bible insists that a vow, once taken, must be kept: “When a man takes a vow to the Lord, or swears an oath to bind his soul with a bond, he shall not profane his word; he shall do according to all that proceeds out of his mouth,” says Numbers 30:2. But Jewish law recognizes that such vows are often made hastily, out of momentary passions like anger, and without full understanding of their consequences. Indeed, the most famous vow in the Bible is the one Jephthah takes in the Book of Judges, when he promises to sacrifice the first creature he sees on his return home from battle. This turns out to be his daughter, whom he duly kills, since he can’t go back on his word. The tale is practically a fable about the perils of vowing and leaves no doubt that the practice, though common, was never seen by Judaism as particularly admirable.
Earlier Daf Yomi columns are noted here and links.
Tractate Nedarim ("Vows") has now commenced in the Daf Yomi cycle and Ancient Jew Review has posted an introductory bibliography for the tractate: Daf Yomi: Nedarim.