and the second concerns words. If the addition concerns physical actions, it likewise takes one of two forms: it may be an action characteristic of prayer [or one not characteristic of it. If it is an action characteristic of prayer], the prostrations of forgetfulness after the closing salutation suffice when the addition is slight, by agreement; whether they suffice when it is substantial is disputed. A substantial addition is one equivalent to half the prayer or more.
If the action is not characteristic of prayer, it falls into two categories: substantial or slight. If it is substantialโfor example, someone eats, sews his garment, or polishes his sword, and continues doing so for some timeโhis prayer is invalidated, and the prostrations of forgetfulness do not suffice to remedy it.
If it is slight, it takes one of three forms: something permissible during prayer, something disliked during prayer, or something impermissible during prayer. The first requires no prostrations of forgetfulness. An example is when a snake or scorpion passes by someone, and he forgets that he is praying and kills it. Two rulings may be derived concerning the second: one requires the prostrations, while the other does not. An example is when a snake or scorpion passes by someone, and he forgets that he is praying and kills them when neither is threatening him. Concerning the third, one view is that he performs the prostrations and his prayer remains valid; another is that his prayer is invalidated and the prostrations of forgetfulness do not suffice to remedy it. An example is when someone forgets that he is praying and eats or drinks, but does not continue doing so for long.
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If the addition concerns words, it likewise takes one of two forms: the words may be characteristic of prayer or not characteristic of it. If they are characteristic of prayer, there are two opinions as to whether the prostrations of forgetfulness are required. Examples include reciting a surah alongside al-Fฤtihah in the last two units of prayer, remembering Allah between the two prostrations, and similar acts. If the words are not characteristic of prayer, he performs the two prostrations of forgetfulness after the closing salutation.