Do not spit into the well from which you have drunk
See: "A pit from which you have drunk, do not throw a stone into it".
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Translation
Expression (Hebrew)
אַל תִּירַק לַבְּאֵר שֶׁמִּמֶּנָּה שָׁתִיתָ
Definition (Hebrew)
רְאֵה:"בּוֹר שֶׁשָּׁתִיתָ מִמֶּנּוּ אַל תִּזְרֹק בּוֹ אֶבֶן".
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