Shaqiq (may Allah have mercy on him) says that a man came who was called Nahik bin Sinan, and he said: O Abu Abdur Rahman! How do you recite this verse: "of water unaltered" [Surah Muhammad: 15], with a ya' or with an alif? He (Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him)) said: Have you understood the whole Qur'an except this? He said: I recite the Mufassal surahs in a single rak'ah. Sayyiduna Abdullah (may Allah be pleased with him) said: That is like reciting poetry, for the best prayer is the one with much bowing and prostration. People will recite the Qur'an and it will not go down past their throats; but when it is recited, it becomes firmly rooted in the hearts and benefits. I know the similar surahs that the Prophet (peace and blessings be upon him) used to recite, two in each rak'ah. Then he stood up and went away. Alqamah (may Allah have mercy on him) came, and we said: Alqamah! Go and ask Sayyiduna Abdullah (may Allah be pleased with him) about the similar surahs (nazair) that the Prophet (peace and blessings be upon him) used to recite in a single rak'ah. Alqamah (may Allah have mercy on him) asked, and he said: The first twenty surahs of the Mufassal.
(b) "The best prayer is the one with much bowing and prostration."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4688