Who was the commander appointed by the Prophet Muhammad (PBUH) and was not removed by Abu Bakr (RA)?

Who was the commander appointed by the Prophet Muhammad (PBUH) and was not removed by Abu Bakr (RA)?

رسول اللہ صلی اللہ علیہ وسلم نے کون کمانڈر مقرر کیا تھا اور ابوبکر رضی اللہ عنہ نے نہیں ہٹایا تھا؟
Explanation

Usama bin Zaid (RA) was chosen by the Prophet Muhammad (PBUH)

To lead the army against the Byzantine Empire to avenge the Muslim defeat at the Battle of Mutah,


Additional information 

He was the son of Zayd ibn Haritha, Muhammad's adopted son, and Umm Ayman (Barakah), a servant of Muhammad