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.”
Sulaiman b. Yasar quoted Abu Huraira as saying, “I never prayed behind anyone whose prayer more closely resembled that of God’s Messenger than so and so’s.” Sulaiman said that he prayed behind him, and he was prolonging the first two rak'as of the noon prayer, shortening the last two, shortening the afternoon prayer, reciting short suras from al-Mufassal* at the sunset prayer, medium suras from al-Mufassal at the evening prayer, and long ones from al-Mufassal at the morning prayer.
* A name applied to the latter part of the Qur’an because there are many divisions, but opinions differ about where it begins. Lane mentions the different views in his Lexicon, pp 2407 f., saying the most correct opinion is that it begins with sura 49.
Nasa’i transmitted it, and Ibn Majah transmitted up to “shortening the afternoon prayer.”
When I was leading God’s Messenger’s she-camel for him on a journey he said to me, “Shall I not teach you, ‘Uqba, the best two suras to recite?” Then he taught me “Say, I seek refuge in the Lord of the dawn” and “Say, I seek refuge in the Lord of men” (Al-Qur’an; 113-114). He saw that I was not greatly pleased with them, so when he alighted for the Morning Prayer he used them in leading the people in the Morning Prayer, and when he had finished he turned to me and said, “How do you find them now, ‘Uqba?”