It is reported in the athar (the takbir is jazm). Is it authentic as marfu'? And what is its meaning?

The Shaykh : The takbir, as it came in some athar, and some people thought it was a hadith marfu' to the Prophet (peace and blessings be upon him), but it has no basis. What is it? "The takbir is jazm," "The takbir is jazm." It is an athar, not a hadith, and its meaning is not as they imagine, that is, as you hear the Saudi adhan today. You hear it today like this: "Allahu Akbar," "Allahu Akbar," meaning with a normal pronunciation. This has no basis in the Sunnah. In Sahih Muslim, when the mu'adhdhin called the adhan on Friday or on a day other than Friday, and 'Umar was on the minbar, 'Umar said: "Allahu Akbar, Allahu Akbar," meaning he connected the first takbir to the second by moving the dammed ra' according to its natural grammatical position, "Allahu Akbar, Allahu Akbar." This is how the mu'adhdhin says it. And we have been commanded, as he (peace and blessings be upon him) said: What does the mu'adhdhin who follows the Sunnah say? No one answers me or opposes me. As long as the mu'adhdhin in Saudi Arabia says "Allahu Akbar," do we say the same? No, this is not in accordance with the Sunnah. This is acting on a hadith that has no basis. The takbir is jazm. In the Sunnah, the adhan connects the first takbir to the second: "Allahu Akbar, Allahu Akbar." Likewise, the iqamah. But this was confusing for some people who have no knowledge, on one hand of the hadith, and on the other hand of the language. As for the first group of ignorant people, they thought this phrase "the takbir is jazm" was a Prophetic hadith, and it is not so. Rather, it is an athar from Ibrahim al-Nakha'i, who is one of the scholars of the Tabi'un. He said: "The takbir is jazm." And he means that you do not say "Allahu Akbar" by returning to the Shafi'i innovation, but rather that you say "Allahu Akbar."