Explanation of the words of Ibn Malik (may Allah have mercy on him): "And its chapter, and like 'when' which may *** enter this chapter, and it is with some people prevalent."

The Shaykh :"And its chapter" is the chapter of "sanin" (years) among the grammarians. It is every trilateral word whose final letter has been deleted and replaced with the feminine letter "ha," and which has not been broken (i.e., not put into a broken plural). Look at the explanation in front of you.
The student: ... .

The Shaykh : The feminine letter "ha" was added in its place.
The student: ... .

The Shaykh : What? A hundred, yes. Two hundred, good. The chapter of "sanin" or the chapter of "sanin": every trilateral word means every trilateral noun whose final letter has been deleted and replaced with the feminine letter "ha," and which has not been broken, meaning it has not been put into a broken plural. They gave "mi'ah" (a hundred) as an example for this, saying: its plural is "mi'ayn" in the accusative and genitive cases, and "mi'un" in the nominative case. It is also pluralized as "mi'at" as a sound feminine plural, but if it is pluralized as a sound masculine plural, it is attached to it by analogy and is not considered part of it. And the condition that was missed is that it is not a proper noun nor an adjective. Yes, it can be for a masculine and it can be for a feminine; it is not specific to the masculine: "a hundred men" and "a hundred women."
And these things that the author (may Allah have mercy on him) mentioned came from the Arabic language, so it treated them like the sound masculine plural.
He said: "And like 'when' which may *** enter this chapter"
Like "when" which may enter this chapter, the intended meaning is the chapter of "sanin" and what is attached to it. It may occur in the Arabic language like "when." What happens if it occurs like "when"? It is inflected with visible vowel marks on its last letter, and the letter "ya" is obligatory. The letter "ya" is obligatory, just as... "when" is also like this, and it is inflected with visible vowel marks on the "nun." Allah the Exalted said: So "sanin" is inflected like "when," so you say: "I stayed in this land for years (saninan)," just as you say: "I stayed in it for a while (hinan)." "Saninan," good. And if I wanted to attach it to the sound masculine plural, I would say: "I stayed in this land for years (sanin)." The inflection differs. If I say "I stayed in this land for years (saninan)," then "saninan" is a time adverb in the accusative case, and the sign of the adverbial case is a visible fathah. If I say "sanin," I would say "sanin" is attached to the sound masculine plural, in the accusative case with a "ya" in place of the fathah, and the sign of its accusative case is... yes, not in place of the fathah, but the "nun" is a substitute for the tanween in the singular noun.
And among that is the saying of the poet Abd al-Rahman. What is the saying of the poet? "He invited me"
"He invited me from Najd, and its years *** played with us, making us old, and we made the old young"
Good. If it were brought as attached to the sound masculine plural, he would say: "And its years (sanayhi)." "And its years (sanayhi)." And let it be known that some students read "sanayhi" (with shaddah on the ya), and this is a grammatical error, an ugly error, to say: "sanayhi." Rather, he says: "And its years (sanayhi)" or "saninahu." So it is either inflected like "when" with visible vowel marks on the "nun," or inflected like the sound masculine plural with a "ya" in the genitive and accusative cases, and with a "waw" in the nominative case. Good.
If I say: "Many years (sanun) passed over this house," here "Many years (sanun) passed over this house," so I used it now in the usage of what? The usage of "when." So I say: "Ata" is a past tense verb, and "sanun" is the subject, in the nominative case with a visible dammah on its last letter. And if I want to use it in the usage of what is attached to the sound masculine plural, I say: "Many years (sanun) passed over this house." "Sanun," correct. I raise it with a "waw," just as I say: "Muslims (muslimun) came to me," and it is raised with a "waw" in place of the dammah, and the "nun" is open. Yes.
He said: "And like 'when' which may *** enter this chapter, and it is with some people prevalent" meaning that this chapter is prevalent to be like "when," so they do not attach it to the sound masculine plural absolutely. And they consider its attachment to the sound masculine plural incorrect. But this is an error. The correct view is that it is attached to the sound masculine plural in the most eloquent speech. Allah the Exalted said: And He did not say "sanin." So the most eloquent is that it is attached to the sound masculine plural. Yes.
The student: May Allah reward you... sign.

The Shaykh : No, it is not a sign.
The student: ... .

The Shaykh : Yes.
The student: I say why? Why is it taken? Because the scholars observed it and tracked it, and they found that the Arabs...?