Some of the Ahlul –'Ilm
use to say that:
The one who continuously leaves off witr their shahāda (i.e testimony) is not accepted.
Source: Taken from the Lecture Worship Allah Until
Death Comes To You, Day 29, taught by Sheikh Hassan Somali at Masjid As-Sunnah
An-Nabawiyyah Germantown Masjid, Philadelphia, 20:38-51/22:13 GMT Time, Germantown
Masjid (Youtube channel)