Kiddushin 59B

מעשה מוציא מיד מעשה ומיד מחשבה, מחשבה אין מוציאה לא מיד מעשה ולא מיד מחשבה. בשלמא מיד מעשה לא מפקה, דלא אתי דיבור ומבטל מעשה, אלא מיד מחשבה מיהא תפיק!

An action undertaken to improve the vessel negates both the status created by an earlier action that supposedly completed the vessel and the status created by the thought not to perform more work on the vessel. In that case the vessel cannot contract ritual impurity until the craftsman has finished working on it. By contrast, a thought to improve the vessel negates neither status created by action nor status created by thought. Reish Lakish finds this difficult for the following reason: Granted, thought does not negate action, as a statement does not come and nullify action. But it should at least offset thought. This halakha indicates that a statement does not nullify a previous statement.

שאני מחשבה דטומאה, דכי מעשה דמי, וכדרב פפא. דרב פפא רמי: כתיב: ״כי יתן״, וקרינן: ״כי יותן״. הא כיצד?

The Talmud answers: Thought in the case of ritual impurity is different, as it is considered like action, and this is in accordance with the opinion of Rav Pappa. As Rav Pappa raises a contradiction: With regard to the halakha that produce must become wet in order for it to contract ritual impurity, the verse states: “But if water is placed [vekhi yuttan] upon the seed, and any part of a carcass falls upon it, it is impure” (Leviticus 11:38). The word yuttan is written defective, and is written as if it says ki yitten. Accordingly, this would mean that one must actively place the water on the produce. Yet we read it, based on the tradition as to its correct pronunciation, “ki yuttan,” which includes any situation where the produce becomes wet. How so? How can the way the verse is written and the way it is read be reconciled?