[The Perfect Words]

Answer—and Allah is the One Who grants success and assistance: The “words” here can be explained as the power of Allah—Exalted is He. And they came in the plural form, considering their penetration into everything, in every place and time, and in all states.
And what supports this explanation is what came in another ḥadīth from the Prophet (May Allah bless him and his family and grant them peace): "Place your hand on the place of pain seven times and say: I seek refuge in the might of Allah and His power from the evil of what I find"—or as he said.
And this may be supported by His—Exalted is He—saying: "And the best word of your Lord was fulfilled for the Children of Israel because they were patient" [Al-A‘raf:137]; for the meaning of that is: that Allah—Exalted is He—brought to pass for the Children of Israel and did for them, by His power, what had preceded as the promise from Allah to them of succession in the earth and the good end; so Allah—Exalted is He—named the doing of that a “word.”
And His—Exalted is He—saying: "His command, when He intends a thing, is only that He says to it, ‘Be,’ and it is" [Ya-Sin:82]; so Allah—Glorified and Exalted—is He—expressed His power and the speed of its effect by the word “Be.”
And the words were described with perfection in his saying: "the perfect" in order to clarify the penetration of the power of Allah—Exalted is He—and that nothing incapacitates it, and no obstacle stands in its way.
And among that is His—Exalted is He—saying: "And Allah eliminates falsehood and establishes truth by His words; indeed He is Knowing of what is within the breasts" [Ash-Shura:24].
And from this figurative usage is His—Exalted is He—saying regarding ‘Īsā: "… the Messenger of Allah and His word which He cast to Maryam, and a spirit from Him" [An-Nisa’:171].
This—and it may be intended by “the words” the Qur’an; and it was permitted to seek refuge by it due to what it has of distinctiveness and clear connection to Allah—Exalted is He—so seeking refuge by it is seeking refuge in Allah; and from here it was not permitted for the menstruating woman and the one in major ritual impurity to recite it nor to touch it.
And it may be intended by “the words” knowledge; for “words” may be used and knowledge intended by them, as in His—Exalted is He—saying: "And if whatever trees upon the earth were pens, and the sea were ink, replenished thereafter by seven more seas, the words of Allah would not be exhausted" [Luqman:27].
And this meaning is near and suitable for the context: for indeed the knowledge of Allah—Exalted is He—has encompassed everything; so it is fitting that a person seek refuge from the evil of everything encompassed by the knowledge of Allah—Exalted is He—.
And from this figurative usage as well is His—Exalted is He—saying: "Say, if the sea were ink for the words of my Lord, the sea would be exhausted before the words of my Lord were exhausted, even if We brought the like of it as a supplement" [Al-Kahf:109].

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3