Is it permissible to perform sa'i in a wheelchair?

Yes, it is permissible to perform sa'i in a wheelchair if one is unable to walk. The general principle is that inability to perform an act in its default manner does not remove the obligation — it shifts to what is possible. Sheikh Ibn Uthaymeen stated: 'The one who cannot walk in sa'i may ride or be pushed in a wheelchair. سعی is a pillar and must be performed.' The wheelchair user still counts 7 laps between Safa and Marwa. There is no fidyah required for performing sa'i while seated.