You know that you should put the source as per howto:upload or use source_request. This tag exist for some reason. The same goes for other Contributors, too. It's not only you.
You know that you should put the source as per howto:upload or use source_request. This tag exist for some reason.
If you don't know the image's source anymore (e.g. it's a file you saved to your computer in the past) you can try to use a Reverse Image Search Engine to find the source of the image.
I don't see the need to spend half an hour or more trolling the internet to find where the original source for an image that's been on my HDD for 3 years is. If you have the free time, feel free to take it upon yourself to do so.