Let your friend's money be as dear to you as your own/ Let your neighbour's property (money) be as precious to you as your own!
Your friend's money should be as precious in your eyes as your own money. You should feel concern for another person's financial or economic well-being just as you do for your own.
("Rabbi Yosei says: Let your friend's money be as dear to you as your own, and prepare yourself to study Torah, which is not inherited by you, and let all your deeds be for the sake of Heaven" - Avot 2:12)
Translation
Expression (Hebrew)
יְהִי מָמוֹן חֲבֵרְךָ חָבִיב עָלֶיךָ כְּשֶׁלְּךָ
Definition (Hebrew)
כַּסְפּוֹ שֶׁל חֲבֵרְךָ צָרִיךְ לִהְיוֹת יָקָר בְּעֵינֶיךָ כְּמוֹ כַּסְפְּךָ שֶׁלְּךָ. גָּלָה דְּאָגָה לְגוֹרָלוֹ הַכַּסְפִּי אוֹ הַכַּלְכָּלִי שֶׁל זוּלָתְךָ כְּשֵׁם שֶׁאַתָּה דּוֹאֵג לְשֶׁלְּךָ.
("רַבִּי יוֹסֵי אוֹמֵר יְהִי מָמוֹן חֲבֵרְךָ חָבִיב עָלֶיךָ כְּשֶׁלָּךְ וְהַתְקֵן עַצְמְךָ לִלְמֹד תּוֹרָה שֶׁאֵינָהּ יְרֻשָּׁה לָךְ וְכָל מַעֲשֶׂיךָ יִהְיוּ לְשֵׁם שָׁמַיִם"-אָבוֹת ב יָא-יב)