A. Dietrich Ringle:
What are the Yoga Sutras? Link?
Thanks
The Yoga Sutras are post Buddhist Hindu teaching about liberation written supposedly by Patanjali in Sanskrit. Patanjali is revered as the founder of yoga although his sutras have very little to do with hatha yoga or physical exercises. Here is one translation.
https://www.sacred-texts.com/hin/yogasutr.htm
If you take a look you'll see that The Yoga Sutras are very terse. They're usually accompanied by a commentary expanding on the base text. Here's one such which I found useful.
http://www.swamij.com/yoga-sutras-list.htm
There's a lot of value in the Yoga Sutras but I would be remiss if I didn't point out that they are not Buddhist and their presentation of siddhis isn't a Buddist one. See here
https://en.wikipedia.org/wiki/Iddhipada
and here for one of the Pali suttas on iddhis in the Theravadan tradition.
https://www.accesstoinsight.org/tipitaka/sn/sn51/sn51.020.than.html