"And I spake unto him, even with an oath...," 1 Nephi 4:33.
"Behold, the days come, saith the Lord, that I will perform that good thing which I have promised unto the house of Israel and to the house of Judah," Jeremiah 33:14.
There was a time, when the words 'I promise' were as good as a contract. To be a person that keeps their word in this day and age is a rare thing. When we keep our promises, we feel clean and filled with joy. As a little girl, I remember my mother was ever so careful to say 'we'll see' instead of 'I promise.' Truthful and diligent, she abhorred disappointing people. Although I pretty much failed as a mother and my children have grown into pretty good people in spite of me, at least I kept my promises or refused to enter into such a contract. I remember one child in particular always tried to press me into making a definite answer. Finally, I learned to say 'If you need an immediate answer, then it is no. If you can wait until I can consult with your father, then it is maybe."
When I got hurt on our mission, I wanted to ask for an honorable release. Instead, I kept my promise, remaining to protect the property but able to do very little physical work. It was so hard. However, when the time wound down, I felt joy and satisfaction for sticking it out to the end as promised.