'Be Strong' in the Bible

This is what the Lord of armies has said: Let your hands be strong, you who are now hearing these words from the mouths of the prophets, that is to say, in the days when the base of the house of the Lord of armies has been put in place for the building of the house, that is the Temple.

And it will come about that, as you were a curse among the nations, O children of Judah and children of Israel, so I will give you salvation and you will be a blessing: have no fear and let your hands be strong.