Al-Bukhari mentioned on the authority of Salamah bin Al-Akwa’ that he said: The Messenger of God, may God’s prayers and peace be upon him, ordered a man from Islam to call out to the people: whoever has eaten, let him complete the rest of his day, and whoever has not eaten, let him fast, for today is the day of Ashura.

So he made his ruling the rule of those who did not eat. Someone who doubted the first day of Ramadan did not fast overnight and ate, then it was proven that it was Ramadan, so he commanded abstaining and making up for it, and this is an authentic hadith. He said, “Let him complete the rest of his day,” and he did not call him fasting, so this hadith strengthens the hadith about making up for fasting, which Abu Dawud mentioned on the authority of Abd al-Rahman ibn Salamah on the authority of his uncle if he converted to Islam .