What is the ruling if a man enters the mosque and sees the imam bowing, so he bows and walks while bowing until he joins the row?

The questioner : ... and he is walking.

The Shaykh: Yes.

The questioner : ... behind the row?

The Shaykh : That is from the Sunnah.

The questioner : The prayer, yes, .

The Shaykh : No, no, this is not it; this is by deduction. As for what I am saying, it is by explicit text: "It is from the Sunnah that if a person enters the mosque and finds the imam bowing, he should bow where he is, then creep along until he joins the row."

The questioner: Yes.

Another questioner : Is this a hadith of my shaykh?

The Shaykh : It is in al-Hakim's al-Mustadrak.

The questioner : May Allah reward you with good.

The Shaykh : And to you.

The questioner : The hadith with this wording?

The Shaykh : Yes.

The questioner : ... ؟
The student : In al-Hakim's al-Mustadrak, yes, yes.
Another student: Is this one or that one, O Shaykh?

The Shaykh : No, it is this one; perhaps it is this one.

The questioner : ... Our Shaykh, are you saying there is an addition in it?
Another student: It is authentic.

The Shaykh : In the name of Allah.

The questioner : I thought the Shaykh meant to say something about it.
The student : He considers it a Sunnah.
Another student: Come closer to the table, O Shaykh.