Ibn al-Mubarak narrated it in al-Zuhd (no. 797): Yahya ibn Ayyub informed us, from Amr ibn al-Harith, from Bakr ibn Sawadah, relating the same report.

I say: This chain of transmission consists of trustworthy narrators who are among Muslim’s narrators, but I do not know whether Bakr ibn Sawadah heard from Abu al-Darda or not. Nevertheless, it is an acceptable corroborating report for the mursal narration. Although it is attributed to the Companion, it carries the status of a report attributed to the Prophet, since such a statement cannot be based on personal opinion—especially as it has also been narrated from him as a report attributed to the Prophet. Al-Hakim al-Tirmidhi likewise cited it in The Book of the Astute and the Deluded (p. 78, al-Zahiriyyah manuscript), and al-Suyuti also attributed it in al-Jami to al-Hakim on his authority—that is, in Nawadir al-Usul. Al-Manawi stated that its chain of transmission is weak. And Allah knows best.

1352 — “Never regard any act of kindness as insignificant, even if you pour from your bucket into the vessel of one seeking water, or speak to your brother while facing him with a cheerful expression. Beware of letting your lower garment trail, for that is arrogance, and Allah does not love arrogance. If a man insults you for something he knows about you, do not insult him for something you know about him, for its reward will be yours and its evil consequence will be upon the one who says it.”

Ahmad narrated it (5/63): Yazid related to us; Salam ibn Miskin informed us, from Uqayl ibn Talhah, who said: Abu Jurayy al-Hujaymi related to us: “I came to the Messenger of Allah, peace and blessings be upon him, and said: ‘O Messenger of Allah, we are a people of the desert, so teach us something through which Allah may benefit us.’” He then related it. He also narrated it from Abd al-Samad, from Salam, with the same chain, except that he said: “Do not revile him for what you know about him, for the reward of that will be yours and its evil consequence will be upon him.”

This is an authentic chain of transmission. Its narrators are those of al-Bukhari and Muslim, apart from Uqayl ibn Talhah; he is trustworthy, and his father was a Companion, as stated in al-Taqrib.