Why Moses Prayed With Words of Pleading at Vaetchanan

Another interpretation: "And I pleaded with the Lord" (Deuteronomy 3:23). This is what Scripture says: "And You shall hearken to the supplication of Your servant" (1 Kings 8:30). By many names is prayer called: prayer (tefillah), supplication (techinah), shouting (tze'akah), crying out (ze'akah), beseeching (shav'ah), glad song (renanah), entreaty (pegi'ah), groaning (ne'akah), calling (keri'ah), petition (atirah), standing (amidah), and imploring (chiluy). Why did Moses pray only in the language of pleadings (tachanunim), as it is said, "And I pleaded with the Lord"? Rather, at the hour when Moses stood and said before the Holy One, blessed be He, "Show me, please, Your glory" (Exodus 33:18), he said to Him: Master of the World, show me, please, by which measure You guide Your world. The Holy One, blessed be He, said to him: I will show you. "And He said: I will cause all My goodness to pass before you" (Exodus 33:19). The Holy One, blessed be He, said to him: I am not obligated to any creature in anything; rather, freely (as a gift) do I give to them, as it is said, "And I will be gracious to whom I will be gracious" (Exodus 33:19). Moses said to Him: If so, do with me a kindness and give to me freely (as a gift). Therefore he said, "And I pleaded."