Dear Bosses!
I have used the following pattern as the background of my WordPress theme.
The fact is that the pattern is collected from Google searching and has no license.
Does it cause any issue for Themeforest approval?
Thank you all so much for reading 
!
You can’t use an image from Google that you don’t have permission to use.
The fact it has no license makes it sound like it would be easier to use than if it did have a license, but it;s quite the opposite unfortunately. A license will at least tell you if you can’t or can’t use the item for your intended usage. A lack of license basically means that it belongs to somebody other than yourself, isn’t available for licensing, and you can’t use it in any way shape or form.
Although, if you mean it is in the public domain… then you might be able to use it. But you need to check that it really is int eh public domain. Bottom line, you need permission to use any item in an Envato item. If you don;t have permission (either specifically from the author of the item or in-line with the terms of any license) then you can’t use it.
Thanks much. 
Can I use patterns from this site without permission?
Or, can you share any sites where I can use patterns without permission from?
Thanks again for your kind reply.
Read the FAQ page on that site… the answer is in there about whether you can use their items in your items. That may not wash with Envato though, as I have no idea if you can add lines of code to Themes directing to external sites and crediting them for the pattern.
I found this FAQ from https://www.toptal.com/designers/subtlepatterns/
Now my query is…
Does that answer mean that I have to mention their site url in the theme description which is written on the themeforest theme description?
@SpaceStockFootage