The one who cast the evil eye would be ordered to perform ablution, and then the one afflicted by it would wash himself with that water.
حدثنا عثمان بن أبي شيبة حدثنا جرير عن الأعمش عن إبراهيم عن الأسود
كان يؤمر العائن فيتوضأ ثم يغتسل منه المعين
[Its chain is daif] Bayhaqi narrated it, 9/351, through Abu Dawud with the same chain, and its chain is daif. Amash and Ibrahim narrated with "an" (indicating a possible break in transmission).