This morning I went to a local church where they meet one hour earlier than my home church. My mission was to invite them to our praise & worship service this evening. I'd preached at this church before. When I walked in the door I was greeted with "Good, we've got a preacher after all". I thought they were kidding me, but no. Their pastor took the week off for holiday.
I asked if they were serious about wanting a sermon and they said that they weren't going to let me leave without one. I had prepared a sermon for our Sunday night service, and why I brought a copy of it with me to visit that church is beyond me. We all agreed that it was the Holy Spirit who put that sermon in my hands as I left this morning, because He knew it would be needed before tonight!
As I was leaving I thanked them for giving me an opportunity to do a first run with tonight's sermon...and asked them to come tonight to see the more polished version. God works in mysterious ways!