Nedarim 8:3-4

Nedarim 8:3

If one vows not to taste wine “until the grain harvest,” “until the grape harvest” or “until the olive harvest,” he is only prohibited until that time arrives. The general principle is that whenever a thing has a designated time, “until it arrives” prohibits until it arrives and “until it will be” prohibits until it passes. If a thing does not have a designated time, “until it will be” and “until it arrives” both prohibit only until the thing arrives.

Nedarim 8:4

If one vows “until summer” or “until it will be summer,” he is only prohibited until the people start to bring in baskets of figs from their harvests. If he says “until summer passes,” he is prohibited until the people pack up their fig-cutters. “Until the harvest” means when the people start harvesting wheat, not barley. Everything follows the place where one vows: if he is in the mountains, he is prohibited until the harvest arrives in the mountains; if he is in the valleys, he is prohibited until the harvest arrives in the valleys.