Imam Ahmad recorded that `Irbad bin Sariyah said that the Messenger of Allah ﷺ used to recite Al-Musabbihat before he went to sleep, saying,
«إِنَّ فِيهِنَّ آيَةً أَفْضَلُ مِنْ أَلْفِ آيَة»
(In them there is an Ayah that is better than a thousand Ayat.) Abu Dawud, At-Tirmidhi and An-Nasa'i collected this Hadith; At-Tirmidhi said, "Hasan Gharib." The Ayah referred to in this Hadith is -- and Allah knows best --
(He is Al-Awwal and Al-Akhir, Az-Zahir and Al-Batin. And He is the All-Knower of everything.)(57:3) Allah willing, we will again mention this subject. Upon Allah we trust and our total reliance and dependence are on Him, and sufficient He is to us as Supporter and Helper.
It is recorded in Abu Dawud, Tirmidhi and Nasa'i that Sayyidna ` Irbad Ibn Sariyah ؓ said that the Messenger of Allah ﷺ used to recite Al-Musabbihat before he went to sleep and said: "In them there is a verse that is more meritorious than a thousand verses." The collective name of the series Al-Musabbihat refers to the following five Surahs: [ 1] Al-Hadid; [ 2] Al-Hashar; [ 3] As-Saff; [ 4] Jumu'ah; and [ 5] At-Taghabun. Having cited this Hadith, Ibn Kathir says that the best verse referred to in Surah Al-Hadid is verse [ 3] هُوَ الْأَوَّلُ وَالْآخِرُ وَالظَّاهِرُ وَالْبَاطِنُ ۖ وَهُوَ بِكُلِّ شَيْءٍ عَلِيمٌ (He is the First and the Last, and the Manifest and the Hidden, and He is All-Knowing about everything....57:3] Among the five Surahs, the first three, namely Al-Hadid, Al-Hashr and As-Saff commence with the past perfect tense 'sabbaha' [ purity has been proclaimed ] whilst the last two, namely Al-Jumu` ah and Al-Taghabun commence with the imperfect tense yusabbihu [ purity is proclaimed ]. This implies that the purity of Allah should be declared at all times, the past, the present and the future. [ Mazhari ]
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.