Rogue poison quest

So recently during the second quarantine I decided to hop on the game again and continued playing on my undead rogue but recently after hitting lvl 60 I realised I dont have any poisons at all , so I searched and apparently you get those from a questline which I haven't completed (probably abandoned them which was very dumb from my part) and I went to all the rogue trainers in Undercity and Oggrimar but I haven't really found out where to get it from.What should I do?

You just buy the poisons from vendors, you don't have to brew them.

if u can list their locations I would appreciate it a lot if not thanks for the help and happy holidays

This may be a bit outdated but it will give you an idea https://wow.gamepedia.com/Poison_vendor

Just enable Poisons tracking on your minimap and it will track any vendor you can buy poisons from.