The Messenger of Allah ﷺ said, "Whoever fights so that the word of Allah may be supreme is in the cause of Allah."
حدثنا يحيى بن آدم حدثنا زهير حدثنا منصور عن شقيق
قال رسول الله ﷺ من قاتل لتكون كلمة الله هي العليا فهو في سبيل الله عز وجل
Its chain is sahih, and its narrators are well known. The hadith was narrated by Bukhari 1/217, no. 122, in Fath al-Bari, in the Book of Knowledge, in the chapter on what is recommended for the scholar when asked, and Muslim 3/1512, no. 1904, in the Book of Leadership, and Tirmidhi 4/153, no. 1646, in the Book of jihad, in the chapter on one who fights for show, and he said, hasan sahih, and Nasai 6/23, no. 3136, and Ibn Majah 2/931, no. 2783, and Abdul-Razzaq 5/268, no. 9567.