What was the reason for the revelation of Allah's saying: (And do not drive away those who invoke their Lord morning and evening)?

The reason for the revelation of the verse: (And do not drive away those who invoke their Lord morning and evening, seeking His countenance) is that the polytheists asked the Prophet, peace and blessings be upon him, to drive away some poor Companions, such as Ibn Mas'ud and Bilal, so that they might sit with him. The Prophet intended to do so, whereupon the verse was revealed, prohibiting him from driving them away.