Or HaChaim on Numbers 12:13/אור החיים על במדבר י״ב:י״ג

1 ויצעק משה אל השם, Moses cried out to G'd, etc. The reason the Torah added the word לאמור, was to tell G'd that he had not felt offended at all and that such an assumption should not result in Miriam and Aaron assuming that he harboured some enmity against them although he wanted Miriam to be cured. It had been Aaron's words in verse 12 which had made Moses feel that he had to indicate that he never harboured any resentment against them.

2The word לאמור may also mean that before Moses commenced his prayer he told G'd that as far as he, personally, was concerned he had waived any honour due him so that he did not feel slighted.

3א-ל נא רפא נא לה. "Please O Lord, heal her." Moses addressed the attribute of חסד, similar to Psalms 52,3 where David speaks of חסד קל. [According to Rabbi Moshe Alshich the חסד, "kindness" of G'd's anger, is its very brevity. It lasts a second, no more. Ed.] The words רפא נא are a plea to grant the cure immediately.