We were with Ammar on the day of doubt when a roasted sheep was brought to him. Some of the people withdrew, so Ammar said, "Whoever fasts on this day has disobeyed Abu Qasim ﷺ."
حدثنا محمد بن عبد الله بن نمير حدثنا أبو خالد الأحمر عن عمرو بن قيس عن أبي إسحق
كنا عند عمار في اليوم الذي يشك فيه فأتى بشاة فتنحى بعض القوم فقال عمار من صام هذا اليوم فقد عصى أبا القاسم ﷺ
[Its chain is daif]. Tirmidhi narrated it in the Book of Fasting, chapter on the dislike of fasting the day of doubt, no. 686, and Nasai, no. 2190, and Ibn Majah, no. 1645, through the hadith of Abu Khalid Ahmar, with the same wording. Tirmidhi said, hasan sahih. Bukhari mentioned it without a full chain, no. 1906. Hakim graded it sahih according to the criterion of the two Shaykhs, 1/424, and Dhahabi agreed with him.Abu Ishaq used the vague form "an" in transmitting it, and the hadith has daif corroborating narrations.