New answers tagged intoxication
The statement is made in what appears to be an addendum to the 6th letter printed at the end of Ateres Tzvi (the Zitishover's commentary on the Zohar). He makes two similar statements equating drinking on Purim to fasting for 6 days. He does not source the idea but compares it to the fasting of Mar b'rei d'Ravina (of which I am unfamiliar).
Sefer Segulas Yisrael 80:3 is the source you are looking for.
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