אַל־תֹּאמַ֗ר כַּאֲשֶׁ֣ר עָֽשָׂה־לִ֭י כֵּ֤ן אֶֽעֱשֶׂה־לּ֑וֹ אָשִׁ֖יב לָאִ֣ישׁ כְּפָעֳלֽוֹ׃
Say not: ‘I will do so to him as he hath done to me; I will render to the man according to his work.’
Read kabbalistic (mystical) interpretation of Proverbs 24:29: and classical mystical sources.