I am trying to find the gnome who sold the poison and searched through the whole town, Market area even several times, but can't find him! Do I have to do something first or is it a bug?

His name is Wallace I believe, and he's in the southern part of town.

Or dude check ur map and it'll tell u where the market place is hit tab on every character u see. It gives out their names and when u see wallace talk 2 him

O, I did talk to Wallice... all he was doing was trying to sell me his goods.

Use Mazzy to talk to him.

I did. No result. I think it must be a bug.

Have you fully patched your game?

If you do not have ToB, make sure you have the following patches. Install the official patch before the Fixpack.

Official SoA Patch
SoA Fixpack v3.61

If you do have ToB, then make sure you have the following patches. As above, install the official patch before the Fixpack.

Official ToB Patch
ToB Fixpack v1.12

If the patch doen't work trying going straight to the local temple and asking the senior priest about Barl.

I tried with patches, it didn't work, I also couldn't speak to priest, so I decided to begin the new game without ToB installed and see if it will work. Thanks for help.