Does the nullification of prayer apply equally to obligatory (Fard) and voluntary (Nawafil) prayers?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
The nullification of prayer applies equally to both obligatory (Fard) and voluntary (Nawafil) prayers. This ruling is based on the general scope of the relevant Hadith which applies to every prayer. Furthermore, the factors that invalidate prayer are treated the same for both obligatory and voluntary acts, thus this invalidating factor must also be equal.
Supporting text
There is reported discourse from Ahmad suggesting leniency regarding voluntary prayers. However, the correct view mandates equality between voluntary and obligatory prayers. Ahmad himself noted that arguments for distinction regarding voluntary prayer are based on the Hadith concerning Aisha, but he maintained that no distinction exists between voluntary and obligatory prayer except for the specific allowance of performing voluntary prayer while mounted on an animal.