Teaching religious knowledge and giving religious verdicts in a masjid

Narrated Nafi`:

`Abdullah bin `Umar said: "A man got up in the mosque and said: O Allah's Messenger (ﷺ) 'At which place you order us that we should assume the Ihram?' Allah's Messenger (ﷺ) replied, 'The residents of Medina should assure the Ihram from Dhil-Hulaifa, the people of Syria from Al-Juhfa and the people of Najd from Qarn." Ibn `Umar further said, "The people consider that Allah's Messenger (ﷺ) had also said, 'The residents of Yemen should assume Ihram from Yalamlam.' " Ibn `Umar used to say, "I do not: remember whether Allah's Messenger (ﷺ) had said the last statement or not?"