Which are the body parts that can be omitted from washing during wudu when necessary?

The person performing ablution (wudu') must wash all the parts of the body involved in ablution. If washing a particular limb causes harm, they should wipe over it. If wiping is not possible, they should place a splint (jabirah) over it and wipe over the splint. If they are unable to do even that, they should leave it and wash the healthy limbs, then perform tayammum (dry ablution) for the remaining parts, according to the Hanbalis and Shafi'is. As for the Malikis and Hanafis, they hold that if most of the limbs are injured, one may suffice with tayammum only. Whoever limits themselves to the obligatory acts of ablution, their ablution is valid, but they miss out on a great reward.