Someone who heard the Prophet ﷺ say, "If the enemy launches a night attack against you, say, 'Ha Mim, they shall not be helped.'"
حدثنا محمود بن غيلان حدثنا وكيع حدثنا سفيان عن أبي إسحق
عمن سمع النبي ﷺ يقول إن بيتكم العدو فقولوا حم لا ينصرون
[Sahih] Abu Dawud narrated it in the Book of Jihad, chapter on a man calling out a battle cry, hadith 2597, from the hadith of Sufyan Thawri with this chain. Hakim graded it sahih according to the criteria of Bukhari and Muslim (2/107), and Dhahabi agreed with him (!). Ibn Kathir also graded it sahih in his Tafsir (4/69). Abu Ishaq explicitly stated that he heard it directly, as recorded by Abdul-Razzaq, hadith 9467.There is also a version on this subject narrated from Salama bin Akwa [Abu Dawud, hadith 2596].