Dear list members,

Apologies if this is an elementary question.

In the Shanti mantra taken from the Taittiriya Upanishad

saha nāvavatu saha nau bhunaktu saha vīryaṁ karavāvahai tejasvi nāvadhītam astu mā vidviṣāvahai

Why is it vidviṣāvahai and not vidveṣāvahai similar to the form dveṣāvahai ?

I couldn't see it listed as an irregular form in MacDonnels grammar for students or his Vedic grammar for students or Whitney.

Thanks,

Harry Spier