Who is the "Amin" (trustworthy one) of the Messenger, peace and blessings be upon him?

If the one referred to as the Messenger's trustworthy (amin) is the man to whom he revealed the names of the hypocrites, then it is Hudhayfah ibn al-Yaman. However, if the one referred to as the trustworthy of Allah and the trustworthy of this Ummah is intended, then it is Abu Ubaydah ibn al-Jarrah, whom the Prophet, peace and blessings be upon him, described as such when the people of Yemen requested someone to teach them the Sunnah and Islam. The trustworthy (amin) is the reliable and pleasing one. Although this characteristic is shared among the Companions, the Prophet singled out some of them with qualities that predominated in them.