Of the acts in this list, the only one not considered farḍ is the intention, which is considered a condition of validity شَرْطُ صِحَّة (A/SM); since it precedes the act of wuḍoo’, it is not considered to be part of it. The other conditions of validity include Islam, discretion, istinjâ’ (cleaning oneself after using the lavatory), removal of barriers such as (t: significant amount of) blood or dough on the wuḍoo’ organs, and using pure water that is wholesomely acquired.
Leaving out any act in this list invalidates the wuḍoo’, because the conditions of validity and the pillars are required for the validity of an act of worship.
According to (A), the only required acts of wuḍoo’ that may be called wâjib (because they are waived if anyone forgets to do them) are: saying bismillâh and wiping the ears. Note that these two are mandatory according to the authorized position of the madh-hab (A/SM), even though they are not on this list because in this book, Imam Ibn Qudâmah (may Allah have mercy on him) counts them among the sunan (recommended acts), which will be listed below.