That's what Satan said in the garden.
And the Wicked Witch to Snow White.
We've only learned "Ithe" before for eat. Why does it become "Ith"? Is it because it's a command?
kind of. Ith is the root of the verb (for example eat is the root of eating in English).
You use the root of the verb when issuing a command.
Is there something odd about the pronunciation of ubhal here? Am Faclair Beag gives /u.əl̪ˠ/ but it sounds more like /u.əv/ to my extremely non-native ears.