If you mean, wenalin, it uses past tense for the same reason it is
often used in commandments: to denote the action as assured. The
servant implores his master so strongly that the action is certain,
thus past voice. Again, such usage is extremely common in Russian, but
not in English, which account for the fact that most scholars refuse
to see a so plain thing.
Vadim Cherny
Yitzhak Sapir wrote:
I would see $bty as a rare alternative form of y$bty. See also Judges
19:11, rd