Let it graze until it becomes unfit/ Let him continue so until he falls himself!/ Give him enough rope and he will hang himself!
In the question: Let him touch you with his own until he is consumed by his own power. Give him rest who troubles you, for in the end he will destroy himself (in the source it is spoken of an animal intended for sacrifice. Defilement means defilement or impurity).
("The female set aside for his Passover offering or the male in its second year shall graze until it becomes unfit and be sold, and its proceeds shall go to a donation" — Pesachim 9:7)
Translation
Expression (Hebrew)
יִרְעֶה עַד שֶׁיִּסְתָּאֵב
Definition (Hebrew)
בְּהַשְׁאָלָה: שֶׁיַּמְשִׁיךְ בְּשֶׁלּוֹ עַד שֶׁיִּתְכַּלֶּה מֵעַצְמוֹ. הַנַּח לוֹ לְמִי שֶׁמַּטְרִיד אוֹתְךָ כִּי סוֹפוֹ שֶׁיַּהֲרֹס אֶת עַצְמוֹ (בַּמָּקוֹר מְדֻבָּר עַל בְּהֵמָה הַמְּיֹעֶדֶת לְקָרְבָּן. הִסְתָּאֲבוּת מַשְׁמָע הִתְנַוְּנוּת אוֹ הִטַּמְּאוּת).
("הַמַּפְרִישׁ נְקֵבָה לְפִסְחוֹ אוֹ זָכָר בֶּן שְׁתֵּי שָׁנִים יִרְעֶה עַד שֶׁיִּסְתָּאֵב וְיִמָּכֵר וְיִפְּלוּ דָּמָיו לִנְדָבָה"- פְּסָחִים ט ז)