Tafsir of An-Nahl 16:46

"Or that He may seize them" (meaning the punishment, or Allah, the Exalted. The first is favored by proximity, and the second by the frequent attribution of the act of 'seizing' to Him, the Exalted, in the Great Quran, given that He—Glory be to Him—is the true actor of it).

"During their movements" (meaning their activity, coming and going. The intended meaning, according to what Ibn Jarir and others narrated from Qatadah, and what was also reported from Ibn Abbas, is: 'in their travels.' The Imam said that interpreting it as such is derived from the saying of the Exalted: "Do not let the movement of those who disbelieve throughout the land deceive you." Alternatively, the meaning is: during the state in which they are moving about to fulfill their schemes and striving to execute them. It has been said that the meaning is: in the state of their tossing and turning on their beds, to the right and left, which has the same meaning as what came in another narration from Ibn Abbas regarding their sleep, though I do not see it as sound. Al-Zajjaj said: The meaning is what encompasses all their movements in their affairs, night or day. The majority favor the first interpretation. 'Seizing' (al-akhdh) originally means to possess or acquire a thing, and here it signifies overpowering and destroying. The prepositional phrase is either in the position of a circumstantial qualifier (hal) or relates to the verb preceding it; the former is more appropriate, considering it is the apparent meaning in its counterpart to come, if Allah wills, though in what precedes it, the latter is more apparent).

"And they will not be able to frustrate [Allah]"

"By escaping from Allah, the Exalted, through fleeing," as the state of movement and travel might suggest, "or they are not capable of resisting," as their schemes and movements within them might suggest. The 'fa' (in 'fama') is said to be for explaining the cause of the seizing, or for sequencing the impossibility of frustration upon the act of seizing, as an indication of its intensity and severity, just as the Prophet, peace and blessings be upon him, said: "Indeed, Allah gives respite to the oppressor, but when He seizes him, He does not let him escape." The nominal sentence indicates the permanence of the negation, and the emphasis returns to that as well.