1 Nephi 4: 32-33, 37

Your word should be your bond. People should be able to believe what you say and trust that you'll follow through.

"...as the Lord liveth, and as I live, even so that if he would hearken unto our words, we would spare his life."

"And I spake unto him, even with an oath, that he need not fear; that he should be a free man like unto us if he would go down in the wilderness with us."

"And it came to pass that when Zoram had made an oath unto us, our fears did cease concerning him."