Evil Eye endangers Windfalls

 Eruvin (64a) should he who took possession of the property of a proselyte do that he shall be worthy of retaining it? Let him purchase with it a scroll of the Law’. R. Shesheth said: Even a husband [should act in a similar manner] with his wife's estate. Raba said: Even a man who engaged in trade and made a large profit should act in a similar manner. R. Papa said: Even he who has found something [should act in the same manner]. R. Nahman b. Isaac said: Even if he had only arranged for the writing of one pair of1 tefillin.2 In connection with this R. Hanin [or, as some say: R. Hanina] stated: What is the Scriptural proof?3 It is written: And Israel vowed a vow etc.

Rashi (Eruvin 64a) Any large gain acquired without effort should be used for a mitzva to protect it from the Evil Eye