Why was Abu Ubaidah ibn al-Jarrah (may Allah be pleased with him) called the "Trustee of the Ummah," and what was the reason for him being given that title by the Messenger of Allah (peace and blessings of Allah be upon him)?

Abu Ubaydah Amir ibn al-Jarrah is one of the Ten Promised Paradise, and he witnessed Badr and Hudaybiyyah. He died at the age of 58 due to the Plague of Emmaus in Al-Sham.

Among his significant actions was his leadership of the expedition of Dhat al-Tamrah, where the Companions would eat and suck on a single date. They also discovered the marine creature "Al-Anbar" (ambergris whale), from which they ate for a month. As for his asceticism, when Umar ibn al-Khattab visited him in Al-Sham, he found nothing in his house but his sword, shield, and saddle.

As for the title "Amin Hadhihi al-Ummah" (Trustee of this Nation), it came about when the people of Najran asked the Prophet, peace and blessings be upon him, to send with them a trustworthy man. So the Prophet, peace and blessings be upon him, said: "(This is the trustee of this nation)," referring to Abu Ubaydah. This title does not negate trustworthiness from other Companions, but it indicates that trustworthiness was a predominant and distinguishing characteristic of his.