2,636. Retracting "Toch K'dei Dibbur"

Hilchos Shevuos 2:16

Pursuant to the previous halacha, when judges impose an oath on someone, they instruct him that they aren’t doing so based on his intentions, but on their own.

Hilchos Shevuos 2:17

Let’s say that someone took an oath and, at the time of the oath, his words and his intentions agreed. After the thing he swore about became prohibited to him, he immediately changed his mind. If within the time that it takes to speak he says that it’s not an oath, that he retracts his words, or similar things that indicate that he wants to undo the prohibition that he accepted, it becomes permitted to him. The oath is canceled because it’s like he made a statement in error. The definition of “the time that it takes to speak” is the time that it takes a student to greet his teacher with the words “shalom alecha, rebbe.”