Musnad Ahmad 3:65

Muhammad ibn Ja‘far narrated to us, Kahmas narrated to us, Mus‘ab ibn Thabit ibn ‘Abdullah ibn al-Zubayr narrated to us, he said: ‘Uthman said while he was delivering a sermon upon his pulpit: "I am narrating to you a hadith that I heard from the Messenger of Allah, may Allah bless him and grant him peace. Nothing prevented me from narrating it to you except for my concern for you. I heard the Messenger of Allah, may Allah bless him and grant him peace, say: 'A night of guard duty in the way of Allah is better than a thousand nights spent in prayer during their nights and fasting during their days.'"