I have a question about Surah Taha. What is the meaning of the sentence Istana'tuka li Nafsi?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Allaah Says to the Prophet Moosaa (what means): {And I have chosen you for Myself}[Quran 20:41], Ibn Katheer said regarding the interpretation of the above verse: 'That is to say I have chosen you as a Prophet for Myself, as I Wish.' However, Imaam Al-Bukhari said about the interpretation of the above verse: ' …..Abu Hurayrah, narrated that the Prophet said: "The pious people Aadam and Moosaa (Moses), may Allaah exalt their mention, met and Aadam said: “And it is you [i.e. Moosaa] whom Allaah has chosen for His Message and Revelation and He had chosen you for Himself."

Nonetheless, Imaam Al-Qurtubi said: 'Ibn 'Abbaas interpreted the above verse to mean: 'I have chosen you for My Message and Revelation.' The verse is also interpreted to mean 'I created you, as the Arabic word ‘Istana’tuka’ is derived from ‘As-Sin’ah’ which means profession and craftsmanship. It is also interpreted to mean 'I strengthened you and taught you in order to inform My Slaves about My Commandments and Prohibitions.'  

Allaah Knows best.