A more thorough explanation:

Adjuration is a serious request or plea. It can also mean a solemn oath or promise.

• When the judge asked the witness to tell the truth, he did so under adjuration.
• The priest made an adjuration to the congregation to live a virtuous life.
• Before taking office, the president-elect must make an adjuration to uphold the Constitution.

These examples show how adjuration is used to describe a serious request or oath. In each case, the person is making a solemn promise or plea that carries weight and importance.