Alma 51:33

And it came to pass that when the night had come, Teancum and his servant stole forth and went out by night, and went into the camp of Amalickiah; and behold, sleep had overpowered them, because of their much fatigue, which was caused by the labors and heat of the day.

When night came, Teancum and his servant snuck out. They went into Amalickiah’s camp. The Lamanites were asleep because they were very tired from working hard in the heat all day.

After night fell, Teancum and his servant slipped out and crept into Amalickiah’s camp. The Lamanites were exhausted from the day’s hard fighting and heat, and sleep had overtaken them.