so he takes out the paper and begins writing it down while praying, fearing that if he leaves his prayer, he will forget it.

This is excessive movement that invalidates the prayer. But if it is only one or two words, it is slight; if he needs to do that, there is no harm in it. At times, a person has some necessary matter that he must remember. When a person enters the prayer, Satan comes to him and begins saying, “Remember such-and-such; remember such-and-such”—reminding him of what he had not remembered until he does remember it—not out of compassion for him, but in order to spoil his worship, so that the prayer remains a body without a soul.

His statement, “from other than the acts of prayer,” excludes the case where the movement is extensive but consists of acts belonging to the prayer itself. Actions of the type prescribed in prayer have already been discussed. (1)

His statement, “from other than the acts of prayer,” requires an additional qualification: that such movement be continuous and not necessitated by need. If it is necessary, then it does not invalidate the prayer, even if it is extensive, due to Allah’s saying:

“If you are in fear, then pray on foot or riding.” [al-Baqarah 2:239]

It is well known that those praying on foot will perform considerable movement; those on foot are those who walk upon their feet.

Likewise, if the movements are not continuous—for example, if he performs a slight movement in each rak'ah, which altogether amounts to much movement throughout the rak'ahs—the prayer is not invalidated by it, because it does not conflict with the prayer.

His statement, “Both deliberate and inadvertent movement invalidate it”: as for deliberate movement, this is clear. As for inadvertent movement, the author said that it invalidates the prayer; that is, if a person becomes inattentive for a moment