There are commands in Scripture that are repeated many times. The call to 'stand firm' is one of those commands. It appears all throughout the Bible.
Here are a few powerful verses in Scripture about standing firm:
"Put on the full armor of God, so that you will be able to stand firm against the schemes of the devil."
"Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand."
1 Peter 5:9
"But resist him, firm in your faith, knowing that the same experiences of suffering are being accomplished by your brethren who are in the world."
1 Corinthians 15:58
"Be steadfast, immovable, always abounding in the work of the Lord."
"Conduct yourselves in a manner worthy of the gospel of Christ, so that whether I come and see you or remain absent, I will hear of you that you are standing firm in one spirit, with one mind striving together for the faith of the gospel."
1 Corinthians 16:13
"Be on the alert, stand firm in the faith, act like men, be strong."
"Therefore, my beloved brethren whom I long to see, my joy and crown, in this way stand firm in the Lord, my beloved."