How To Deal With Harassment From Boss?

Dear Seniors,
My boss said to do one work in phone and i did accordingly now he saying,i didnt said to you...and we will terminate you.. how can i prove myself innocent.
Please seniors your advice needed in this

Dear Zubi
Such random and erratic behaviour has more than what appears; it can be a threat or intimidations with bonafide or malafide intention including harassment.
Whether such behaviour is repeated often ??
Just be your own good and strong self and look for alternative solutions.
Warm regards.