Acts 18:9-11 One night the Lord spoke to Paul in a vision and told him, "Don't be afraid! Speak out! Don't be silent! For I am with you, and no one will attack and harm you, for many people in this city belong to me." So Paul stayed there for the next year and a half, teaching the word of God.
I think often we don't speak out for God in places like work... we want to follow the rules... and we break God's rules in doing so... God will be with us if we choose his rules to protect... and if we choose God's rules to protect we are being a witness for God. Often there are lots of people that want to follow God's rules over the rules of work but are afraid to stand up themselves... but when we are brave and do what God ask of us in the face of "human rules" God is with us and it gets other people on board. A dear friend of my told me about being assigned a new job at work... and she told her manager that there were things she couldn't do if she took this job... and that if he was not comfortable with the things she couldn't do he could feel free to ask somebody else.... he choose her for the job and was happy about the things she wouldn't do... those things had made him uncomfortable too... he enjoyed letting her take the credit for following what God wanted over what work wanted, but he supported her 100%... There are many ways to be a witness for God.... choosing what God wants over what man wants is one of the most powerful.