Did Moses (peace be upon him) suffer from a speech impediment when he supplicated to his Lord, "My Lord, expand for me my breast [with assurance] and ease for me my task and untie the knot from my tongue that they may understand my speech," and what is the story behind this verse?

The scholars of tafsir (definition) (exegesis) mentioned that Moses (peace be upon him) had a heaviness and impediment in his tongue, citing as evidence the Almighty's saying: "And my brother Aaron, he is more eloquent in speech than I, so send him with me as a supporter to confirm me. Indeed, I fear that they will deny me." And Al-Tabari clarified that this impediment was due to a burning ember being thrown into his mouth when Pharaoh intended to kill him, and this was at the command of Pharaoh's wife to avert Pharaoh's punishment from him after he had grabbed Pharaoh by his beard.