We came to Ibn Umar on the middle day of the days of Tashriq. Food was brought, and the people drew near, but a son of his kept his distance.Ibn Umar said to him, "Come close and eat."The son replied, "I am fasting."Ibn Umar said, "Do you not know that the Messenger of Allah ﷺ said, 'These are days of eating and remembrance'?"
أتينا ابن عمر في اليوم الأوسط من أيام التشريق، قال: فأتي بطعام، فدنا القوم، وتنحى ابن له. قال: فقال له: ادن فاطعم. قال: فقال: إني صائم. قال: فقال: أما علمت أن رسول الله ﷺ قال: إنها أيام طعم وذكر.
Imam Ahmad (4970) and Nasai in Kubra (2903) both narrated it from the hadith of Husayn bin Ali, from Zaidah, from Ibrahim bin Muhajir, from Abu Shatha, and he related it.Its isnad is hasan due to the discussion surrounding Ibrahim bin Muhajir, who is al-Bajali. There is disagreement about him, but his hadith is graded hasan when it does not contain anything objectionable. It has also been reported as mawquf, but the marfu version is more sahih.