The calculated distance (air line) between Ḩawallī and As Saffānīyah is approximately 103 miles respectively 166 kilometers.
By car or train, the actual journey to As Saffānīyah is certainly longer, as only the direct route (as the crow flies) between Ḩawallī and As Saffānīyah has been calculated here.
Air line (approximately)
166 kilometers
90 nautical miles