GEN1531 One must not arouse other people’s envy. … Yaakov warned his sons against entering Mitzrayim [Egypt] together through one gate, lest they become affected by the evil eye.  Since they were all handsome and strong, he was concerned that an observer’s envy would become aroused. [Rashi, this verse. See also Genesis Rabbah 91:6]. The Talmud Yerushalmi Berachot 4:2 instituted a special prayer to this end: “May it be Your will that I should not become envious of others, and that others should not become envious of me.”   … A person must refrain from displaying his wealth in public or from taking on the appearance of an exceptionally successful person.   One who has been blessed with numerous children should not flaunt them in public.  The only exception, when one may make a public display of his positive deeds, is when giving charity.  However, even this is only commendable if the public pledge will induce others to follow suit.  Otherwise, it is preferable to give charity discreetly.   It is then self-evident that person who makes a public pledge must give a large sum of money, since a pledge for a small amount of money will induce other people to donate only small sums.  WAGS 154-6