But why did 'Umar (may Allah be pleased with him) not pray with them and not pray behind them?

The questioner : ... He did not lead the people in prayer, nor did he pray behind them; because he was ordered... The hadith of the Messenger of Allah (peace and blessings be upon him): 'Umar (may Allah be pleased with him) did not stand with Ubayy ibn Ka'b, nor did he lead the people in prayer himself. He did not gather the people except when he saw them differing, just as the Messenger of Allah (peace and blessings be upon him) saw... So 'Umar (may Allah be pleased with him), when he saw the people... they differed in prayer, some praying here and some praying there, he gathered them for this reason. But he did not pray with them and did not lead them; he did not follow the command of the Messenger (peace and blessings be upon him) to pray with the imam until the reward of standing in night prayer is recorded for him, and he did not lead the people in prayer?

The Shaykh : This is another issue—may Allah bless you—this is another issue; 'Umar did not pray because he was assessing the conditions of the Muslims and investigating their affairs, so what he was doing was better than participating with the people in this prayer. The important thing is that this prayer which 'Umar revived is not a religious innovation, and it is not permissible for a Muslim to call it a religious innovation, even if he calls it a good religious innovation; so how can we say: this is a misguiding religious innovation, and 'Umar ibn al-Khattab ordered it, the Companions responded to it, and the Muslims practiced it until this day?! .

Another questioner : Everyone has the right—may Allah bless you; that is enough for a question.

The questioner : ... the rak'ahs, that the prayer of the Messenger (peace and blessings be upon him) which he prayed was eleven rak'ahs, and then after that... are there recommended practices in the prayer?

The Shaykh : This is contrary to the Sunnah; what do we have to do with this? The Messenger (peace be upon him) did not exceed eleven rak'ahs in Ramadan, and 'Umar ibn al-Khattab ordered Ubayy ibn Ka'b to pray eleven rak'ahs with the people. There is no debate here; we do not deviate from the Sunnah. As for saying: 'Umar innovated, and this is a misguiding religious innovation; rather, we say: he innovated and this is a good religious innovation; this is an error. But "some evil is less than some evil"; the one who says this is a good religious innovation, his evil is less than the one who says: this is a misguiding religious innovation that 'Umar ibn al-Khattab innovated. Far be it from him from this and that; rather, he revived a Sunnah. So his saying (peace be upon him) applies to him: This applies completely to what 'Umar ibn al-Khattab did. This is what I wanted to draw attention to, so that we do not fall— as we said—into excess and deficiency.
For example, some people disapprove of those who are not accustomed to eating with a spoon; well, this has no relation to religion, why is it disapproved? The Messenger (peace and blessings be upon him) did not eat, correct, the Messenger of Allah did not ride a car or an airplane, and so on; so does a person say that this is a religious innovation? Religious innovation is in religion, whereas eating with a spoon, riding an airplane, not riding a beast, and the like; these are all matters of the world, and they may also help us—as we said—such a means in performing some obligations that we may not be able to perform in this time.
The important thing is that we must distinguish between religious innovation in religion and religious innovation in the world.