Mosiah 21:14

And they did humble themselves even in the depths of humility; and they did cry mightily to God; yea, even all the day long did they cry unto their God, that he would deliver them out of their afflictions.

They made themselves as humble as they could be. They cried out to God loudly. They cried to their God all day long. They asked him to save them from their troubles.

They humbled themselves to the very depths. They cried out to God—all day long they cried to him—begging him to deliver them from their suffering.