Permission is granted to copy, distribute and/or modify this image freely for any purpose, including commercial use, as long as the author and the source are credited:
E. Generalic, https://www.periodni.com/images.html
To save the full size image, 3265×2160 px, right-click anywhere on the image and select "Save Picture As..." or "Save Image As...". If you are a Mac user, click and hold on the image until the pop-up selection menu appears, then choose "Save Image".
Crediting is the best way to say thank you.