And appoint for me a helper from my family, Harun, my brother.
This was also a request from Musa concerning something not pertaining to himself. That was his request for the assistance of his brother, Harun.
Ath-Thawri reported from Abu Sa`id, from Ikrimah, who said that Ibn Abbas said,
"Harun was made a Prophet at the same moment that Musa was made a Prophet."
Ibn Abi Hatim recorded that;
A'ishah went out intending to perform Umrah and stopped to camp among some Bedouins. While she was among them she heard a man say, "Which brother in this life was the most beneficial to his brother!"
The people said, "We do not know."
The man said, "By Allah, I know."
A'ishah said, "I said to myself about his swearing, that he should not swear such an oath, singling himself out as knowing what person was of most benefit to his brother."
The man said, "It is Musa, when he asked for Prophethood to be bestowed upon his brother."
Then A'ishah said, "By Allah, he has spoken truthfully."
This is why Allah commended Musa by saying,
وَكَانَ عِندَ اللَّهِ وَجِيهاً
And he was honorable before Allah. (33;69)
Concerning Musa's statement,
اشْدُدْ بِهِ أَزْرِي