How can one maintain steadfastness in faith when distanced from the company of righteous brothers?

You must adhere to the companionship of the righteous. If you part from them, then fear Allah and remember that He, glory be to Him, is watchful over you and that He sees you when you stand and your turning among those who prostrate themselves. So Allah is observing you; therefore, fear Allah and remember that you are before Him. Beware of Allah's punishment and what angers Him. You must be truthful with Allah and steadfast in His religion in your solitude, with your companions, and everywhere, because you are within Allah's hearing and sight; He hears your words and sees your actions. Be more ashamed before Allah, the Exalted, than you are ashamed before your family or others.