Moshe's Egel

Why did Moshe have to break the luchos, put them aside and deal with the Egel first?  Rav Tzaddok (Tzidkas Hatzaddik #154) explains that in order to give rebuke to Klal Yisroel, Moshe had to find an aspect of their sin within himself.  Therefore, Moshe broke the luchos as the Gemorah says כל הכועס כאילו עובד ע"ז.  By getting angry and breaking the luchos, Moshe was attached to the sin of avodah zarah.  We learn from hear a lesson in rebuke; one can only rebuke others if s/he knows what the problem is and how to fix it from within.

          The same idea it says in the Ketem Ofer on the Megillah (4:17.)