Mishkat al-Masabih #797

‘Abdallah b. Mas'ud said: I cannot count how often I heard God’s Messenger reciting in the two rak'as after the sunset prayer and in the two rak'as before the dawn prayer, “Say, O unbelievers,” and “Say, He is God, one God.” Tirmidhi transmitted it, and Ibn Majah transmitted it on Abu Huraira’s authority, but he did not mention “after the sunset prayer.”