After Allah had mentioned Ibrahim, the Friend of Allah, and commended him, he next mentioned Al-Kalim (the one spoken to by Allah directly). Allah said,
(And mention in the Book, Musa. Verily, he was Mukhlasan) Ath-Thawri reported from `Abdul-Aziz bin Rafi`, from Abu Lubabah that he said, "The Disciples (of `Isa) said, `O Spirit of Allah, inform us about the one who is Mukhlis (purely devoted) to Allah.' He said, `That is one who does a deed solely for Allah and he does not like for the people to praise him."' Others recited the word as Mukhlas, which means that he was chosen. This is as Allah says,
"And We, out of our mercy, granted him his brother Harun." - 19:53.
Literal meaning of ھبہ is a gift. Sayyidna Musa (علیہ السلام) had prayed to Allah to grant prophethood to Sayyidna Harun (علیہ السلام) also in order to provide him support. This prayer was granted and the word وَهَبْنَا has been used to describe this episode i.e. the grant of the gift of Harun (علیہ السلام) to Sayyidna Musa (علیہ السلام) . That is why Sayyidna Harun (علیہ السلام) is also known as the Gift of Allah (ھبۃ اللہ). (Mazhari)
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 53–56
Moses, while on his way from Midian to Egypt, passed by the Mount of Tur where God honoured him with prophethood. In every period in the past God selected his messengers (prophets) and entrusted them with His messages. These messages were always sent through the Angel Gabriel. But, in the case of Moses, he was given exceptional treatment, as God talked directly to him. Moreover, Moses was granted a special provision in that God appointed another prophet, Aaron, to assist him. The reason for this special consideration might have been the exceptional circumstances under which he was required to perform his prophetic mission: on the one hand, he had to confront a tyrant, Pharaoh, and on the other, the community of Jews, which had reached the last stage of degradation. God’s Mercy and Help in such abundant measure are bestowed only on His prophets, though God favours his other faithful subjects in the same manner, albeit in varying degrees. God inspires them with divine guidance so that they may perform the task assigned to them. He instills His ideas in their minds. He arranges for them special support the like of which is not available to anybody under ordinary circumstances.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.