If you're still around, to directly address your question, I don't know of any published author who uses Mark 16:9 to prove Jesus rose on the first day. As already noted in this thread, John's gospel makes clear that He had already risen by early the first day, and I've not examined any of the arguments of people who say that Jesus rose on Saturday. That would require that Jesus died on Wednesday crucifixion and an overly-literal 3-days-and-3-nights, both of which I reject anyway. I think it's rather clear that Jesus died on Friday (considering their hurry to get Him off of the cross before the Sabbath--Saturday), and so we can't take it as a Saturday resurrection. Early Sunday seems most appropriate, and I suspect whoever rose Mark 16:9ff simply made what was implicit explicit in their supplied ending.rstrats wrote:I made the mistake of sticking my nose into the discussion by pointing out that actually there is a statement in verse 9, as the KJV has it, that is used for a doctrinal teaching that is to be found nowhere else in Scripture. As the KJV translates it, it is the only place that puts the resurrection on the first day of the week. I then suggested that whenever the discussion of seventh day observance versus first day observance comes up, first day proponents usually use the idea of a first day resurrection to justify the change, and when questioned about the day of resurrection, quote Mark 16:9. The poster came back with: “Quote a published author who has done that.” - I have not yet been able to come up with one. Does anyone here know of one?
So, I hate to say, I rather disagree with your fundamental assumption anyway (that Mark 16:9 teaches something that can't be found elsewhere in Scripture). Beyond that, it should be obvious that the longer ending wouldn't have anything extra due to the nature of the ending; someone wrote it, in light of church history (especially Acts) to provide a "conclusion." Unlike, say, Daniel 9, this really is a case of "prophecy" written after the fact. As such, we wouldn't expect there to be anything beyond what we find in Acts.
For what it's worth, I think there is bad theology in 16:9-20 anyway, which is one of the reasons I reject its authenticity.