Does accidentally (out of forgetfulness) eating or drinking during obligatory or voluntary prayer invalidate the prayer?
Chapter on the Two Prostrations of Forgetfulness
Al-Mughni
Book of Prayer
Primary text
If one eats or drinks during an obligatory or voluntary prayer out of forgetfulness, the prayer is not invalidated. This is the view of 'Ata and Al-Shafi'i. The evidence for this is the general statement of the Prophet, peace and blessings be upon him: 'My Ummah has been pardoned for error and forgetfulness.' Additionally, one is lenient regarding both small and large amounts when the action is unintentional, similar to actions that are part of the prayer itself. The prostration of forgetfulness (Sujud al-Sahw) is prescribed for this error.
Supporting text
Al-Awza'i held that the prayer is invalidated because it is a nullifying action external to the nature of the prayer, thus equating intentionality and forgetfulness, similar to excessive action. However, the prescribed prostration of forgetfulness confirms the leniency for forgetfulness, as any action whose intentional performance invalidates the prayer is excused due to forgetfulness, analogous to an addition of the same nature as the prayer. If such an excused action becomes excessive, it invalidates the prayer without dispute, as minor actions that are excused become nullifying when performed excessively.