Recently I was asked to cover a coworker who lied about why he missed a meeting at work. The truth is that he was driving in late to work and made up a story to his boss that he was meeting with me at the time. Then, he called me and asked me to cover for him in case his boss were to inquire about our meeting. I agreed, but shortly after the phone call I prayed to God that his boss would not ask me about the situation. I didn’t lie, but I did tell my coworker that I would cover for him, and I didn’t bring the truth to his boss. Later on that same day, I emailed the coworker and told him I could not do that for him, and that I would appreciate it if he would not ask such a thing again.
I don’t think I am guilty of lying, but I feel guilty of something. Was this sin of a grave matter?