Answer:
(Fatwa: 1233/1070=L/1429)
If that person is able to stand up and perform salah with ruku and sajdah, then it is not right for him to offer taravih sitting in the chair. In this way, taravih will not be valid.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
