Exodus 23:21

אל תמר בו EXASPERATE HIM NOT — This verb is a term denoting rebellion (המראה), similar to, (Joshua 1:18) “Whosoever he be that rebel (ימרה) against thy commandment”. כי לא ישא לפשעכם FOR HE WILL NOT PARDON YOUR TRESPASS — He is not accustomed to it (to sin) for he is one of a class of beings who never sin. Besides he is only a messenger and only carries out the mission entrusted to him (i. e. he has no right to pardon you, for this is My prerogative: it is his only to insist upon obedience to My commands) (Midrash Tanchuma, Mishpatim 18). כי שמי בקרבו FOR MY NAME IS IN HIM — This passage must be connected with the beginning of the verse: Take heed of him etc. — for (כי) My Name is associated with his (i. e. whatever he does, he does in My Name). Our Rabbis said that he (the angel) is Mattatron (מטטרון) whose name is even as the name of his Master, for מטטרון has the numerical value of שדי “the Almighty” (Sanhedrin 38b).

הִשָּׁ֧מֶר מִפָּנָ֛יו וּשְׁמַ֥ע בְּקֹל֖וֹ אַל־תַּמֵּ֣ר בּ֑וֹ כִּ֣י לֹ֤א יִשָּׂא֙ לְפִשְׁעֲכֶ֔ם כִּ֥י שְׁמִ֖י בְּקִרְבּֽוֹ׃

Take heed of him, and obey his voice, provoke him not; for he will not pardon your transgressions: for my name is in him.