The ruling on standing when hearing the adhan?

The Shaykh : ... I noticed some of our brothers present standing up. I do not want to say that they stood up driven by that habit as usual, but I want to say that their standing reminded me of that habit. This reminder obligates me to remind you that it is a custom that is not prescribed. It is seen in some countries, even in cafes, where two or three people are gathered around a table playing cards or the game of shiddah. As soon as they hear the adhan from the loudspeaker, they stand up. What is this standing for them? It is for the sake of reverence. But true reverence is: "Hayya 'ala al-salah, hayya 'ala al-falah" (Come to prayer, come to success). They stand up and sit down. This is the reverence. And this confirms that Satan has beautified their evil deeds for them. He has convinced them that it is sufficient reverence for Allah that when you hear the mu'adhdhin say "Allahu Akbar, Allahu Akbar," you stand up. But as for "Hayya 'ala al-salah, hayya 'ala al-falah," there is no place for it. This is part of Satan's trickery against his enemy, man, to replace that which is lower with that which is better. So now I saw some of you standing, and I feared that this standing might be from this category. It may not be so, but the important thing is that it is a reminder, and the reminder benefits the believers. So if you see a person actually sitting in a cafe, even if he is drinking coffee or tea, and he stands up and sits down, tell him: "Please, continue with your custom. Come to prayer, come to the mosque." This is the obligatory thing. It is not obligatory, by Allah, that we stand up and sit down as if there is a spring under us, standing and sitting. It is not obligatory to leave one's work. Even if you are reading the Qur'an, not playing cards or shiddah or the like, if you are reading the Qur'an, you must leave this work and go to the mosque. But this standing and sitting, this is from the deeds of Satan.