'Be Strong' in the Bible

And the fourth kingdom shall be strong as iron: forasmuch as iron breaketh in pieces and subdueth all things: and as iron that breaketh all these, shall it break in pieces and bruise.

And said, O man greatly beloved, fear not: peace be to thee, be strong, yes, be strong. And when he had spoken to me, I was strengthened, and said, Let my lord speak; for thou hast strengthened me.

And the king of the south shall be strong, and one of his princes; and he shall be strong above him, and have dominion; his dominion shall be a great dominion.

And such as do wickedly against the covenant shall he corrupt by flatteries: but the people that know their God shall be strong, and do exploits.