The Prophet ﷺ said, "Do not exchange insults while you are fasting. If anyone insults you, say, 'I am fasting.' And if you are standing, sit down."
عن النبي ﷺ قال: لا تساب وأنت صائم، وإن سابك أحد فقل: إني صائم، وإن كنت قائما فاجلس.
Ibn Khuzayma (1994) narrated it, and from him Ibn Hibban (3483), from Muhammad bin Bashshar, who said, Uthman bin Umar told us, Ibn Abu Dhib informed us, from Ajlan, the freedman of Mishmaal, from Abu Hurairah, and he mentioned it.Its chain is hasan because of Ajlan, the freedman of Mishmaal, for his hadith is hasan.Imam Ahmad (9532) narrated it from Yahya bin Saeed, from Ibn Abu Dhib, with his chain, but he did not mention in it, "and if you are standing, then sit down." This is a sahih addition, for Uthman bin Umar was corroborated by Abu Dawud Tayalisi (3259), and by Nasai in Kubra (3259) through the route of Ibn Mubarak. Yazid here is Ibn Harun, and Abu Amir, who is Abdul-Malik bin Amr Aqdi, are both teachers of Ahmad (10564), all of them narrating from Ibn Abu Dhib. It may be that Yahya bin Saeed abridged it.This is a rare practice.