Nedarim, Chapter 7, Mishnah 6. This mishnah addresses the scope of a vow: does the prohibition apply only to the produce itself, or does it extend as well to whatever is received in exchange for it and to whatever grows from it?
Wording of a vow that forbids benefit:
One who says any of these three expressions regarding certain produce:
"Konam peiros ha'eilu alai" - "This produce is konam to me"
"Konam hein al pi" - "They are konam upon my mouth"
"Konam heim l'fi" - "They are konam to my mouth"
With any of these expressions the produce becomes forbidden to him in benefit, and he may not derive any benefit from it at all. In such circumstances the mishnah rules: "assur b'chilufeihen uv'giduleihen" - not only is the produce itself forbidden, but so are the items exchanged for it and whatever grows from it.
What are chilufin and what are gidulin?
Chilufin (exchanges): If he gives the produce to another person and receives money in return (through a sale) or other produce (through a barter), that money and that produce received in exchange are forbidden as well. The reason: since he forbade the produce in benefit, benefit derived from the exchange is likewise considered benefit from the produce.
Gidulin (growths): If he plants this produce in the ground and it grows, those growths are forbidden as well, for the very same reason.
Wording that forbids only eating:
If instead, or in addition, he said "she'ani ochel" - "that I will eat" - or "she'ani to'em" - "that I will taste" - meaning that he will not eat or taste this produce, then he has not forbidden it in benefit but only in eating, and benefit from it is permitted. In this case the mishnah rules: "mutar b'chilufeihen uv'giduleihen" - the exchanges and the growths are permitted. Since he forbade only the eating of that particular produce, whatever results from it, the exchange or the growth, is not included in the prohibition.
Something whose seed decomposes and something whose seed does not decompose:
This leniency regarding growths applies specifically to something whose seed decomposes, that is, produce whose seed disintegrates in the ground, so that the growth is not considered a continuation of the original fruit. But with something whose seed does not decompose, where the seed or the fruit itself does not disintegrate, the law is different. For example, one who plants an onion: the onion grows after it is planted and does not decompose in the ground, and therefore the growths are forbidden, and even the growths of the growths are forbidden, since they still contain part of the original fruit.
In summary: In this mishnah we learned that the scope of the prohibition is determined by the wording of the vow. One who forbids the produce in benefit has also forbidden its exchanges and its growths; but one who forbids himself only in eating and tasting is permitted in its exchanges and its growths. This distinction holds for something whose seed decomposes, but with something whose seed does not decompose the original fruit remains in existence, and therefore even the growths of the growths are forbidden.