The Messenger of Allah ﷺ rarely set out on a journey except on a Thursday.
حدثنا سعيد بن منصور حدثنا عبد الله بن المبارك عن يونس بن يزيد عن الزهري عن عبد الرحمن بن كعب بن مالك
قلما كان رسول الله ﷺ يخرج في سفر إلا يوم الخميس
Bukhari narrated it in the Book of Jihad and Expeditions, chapter "Whoever intends to go on a military expedition but conceals his intent by mentioning another," no. 2948, from the hadith of Ibn Mubarak, with this wording. It is also found in Sunan Saeed bin Mansur, no. 2380, with a slight difference in wording.