I doubt about one thing. ---- collective prayer for non-obligatory prayer.------
are you sure this is not valid. i might need a bit more study about the types of prayers.
what about prayer of eid? and namaz e Janaza and there is another prayer i am forgetting its name. that is also non-obligatory. but we offer it in congregation.
plus i want to add about Hz Umar (RA) he did not do this order in his first year. he thought a lot about it and he did it in his 5th or 6th year of Khalafat. I think he was much experienced and knowledgeable at that time. and from sahabas nobody opposed it.
Best Regards,
I believe I may have used the wrong term. Salat-Eid and Namaz-Janaza are collective prayers by definition and at least namaz-janaaza in my limited knowledge is a fardh namaz to be performed.