´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.”
Explanation & Benefits
Maulana Ataullah Sajid
Benefit:
The aforementioned narration, although weak in its chain of transmission,
yet the issue stated therein—that after accepting Islam, he observed the remaining days of fasting in the blessed month of Ramadan—
is correct.
Because after becoming Muslim, fasting becomes obligatory.
Source: Commentary on Sunan Ibn Mājah by Mawlānā ‘Atā’ullāh Sājid, Page: 1760