'Strength' in the Bible

Then [the leaders of] Judah said,“The strength of the burden bearers is failing,And there is much rubble;We ourselves are unableTo rebuild the wall.”

Then Ezra said to them, “Go [your way], eat the rich festival food, drink the sweet drink, and send portions to him for whom nothing is prepared; for this day is holy to our Lord. And do not be worried, for the joy of the Lord is your strength and your stronghold.”