Shaykh Muḥammad Taqī al-Dīn al-Ḥilālī:

Me and a friend of mine were transferred to teach in the Great Mosque of Mecca; and indeed teaching in the Great Mosque of Mecca is a great trial for the teacher. Often you would find a teacher – well known for knowledge and virtue – sitting and teaching in the Great Mosque of Mecca, yet his gatherings would barely exceed ten people. Then you would find another teacher, someone less than the latter with regards to fame and knowledge, yet you would see hundreds in attendance of his lesson listening. These affairs run in accordance to that which Allah ﷻ has ordained for everyone. Just like you find with shopkeepers; you find one shop frequented with many customers who generate sales whilst the shop next door – even though it stocks the exact same or even better goods  – remains inactive, no customers visit it.

I – and all praise is due to Allah ﷻ – was from the blessed ones. Hundreds would attend my lesson which took place in front of the Gate of Ibrāhīm. I do not know the cause for this except that I used to speak in a dialect that could be understood by all Arabs. As for the other teachers, their lack of attendees was due to them speaking in a local dialect [which could only be understood] by a specific people.