tractate Taanit, page 10B:
Yaakov [Avinu] said to his sons:
“Why do you make yourselves conspicuous?”
Do not allow yourselves to appear well-fed; especially before Eysav,
and especially before Yishmael, so they not become jealous of you.
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Kli Yakar commentary on Devarim, chapter 2, verse 3:
If an Israelite in exile enjoys some small success,
then he must hide it and conceal it completely from Eysav,
because they are more jealous of Israel than any other nation,
because according to their understanding, everything
[that Jews own] was stolen from them…
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Kav HaYashar, Chapter 18:
“Because of our many sins, the Gentiles have their eyes on Jewish wealth.
It is a very good idea to conceal your wealth from them.”