The Shaykh’s reminder of the obligation to use a sutrah in prayer?

The Shaykh : I only intended to remind you of two matters. The first is that when a Muslim enters the mosque, before he begins the greeting of the mosque, the sunnah of wudu, or the sunnah of the time, he should remember that he has an obligation before he begins the prayer. This obligation is to pray facing a sutrah; to pray facing a sutrah. For example, some of our brothers enter this place and one of them prays however it happens. This pole is his sutrah, and that other pole is his sutrah. Then, the brothers who are sitting, each one is sitting facing this direction, so one who wants to pray can pray behind the person sitting, and that person becomes his sutrah.
This is the first matter I want to draw your attention to. We have reminded you of it many times, but we praise Allah (Mighty and Majestic) that in almost every lesson we see new faces who have not previously heard such a reminder and such an exhortation.