سنن ابن ماجه

It was narrated that ‘Atiyyah bin Sufyan bin ‘Abdullah bin Rabi’ah said: “Our delegation who went to the Messenger of Allah (ﷺ) to announce the Islam of Thaqif told us that they came to him in Ramadan. He set up a tent for them in the mosque, and when they became Muslim, they fasted what was left of the month.”