“They said, ‘To You belongs all purity! We have no knowledge except what You have given us. Surely, You alone are the all-knowing, all-wise!' ”Surah Al-Baqarah 32 (Shafi, 2009, p.159) 
Subhana rabbiyal azeem – How glorious is my Lord, the Great;
Subhana rabbiyal a’la – All glory be to My Lord, the Most High.
Subhana rabbiyal a’la – All glory be to My Lord, the Most High – is the tasbih that Rasoolullah (Sall-Allahu alayhi wa-sallam - may the blessings and peace of Allah be upon him) instructed the Sahabah (Radi Allahu Ta’ala’anhum – may Allah be pleased with them) to recite in their sujudfollowing the revelation of the first verse of Surah Al-A’la.
Surah Al-A’la is often classed as one of the Musabbihat Surahs. They are defined as being those Surahs which begin with the glorification of Allah (Subhanahu wa ta’ala - glory be to Him, the Most High).
According to Mufti Muhammad Shafi: “It is recorded in Abu Dawud, Tirmidhi and Nasa'i that Sayyidna 'Irbad Ibn Sariyah (Radi Allahu Ta’ala’anhu – may Allah be pleased with him) said that the Messenger of Allah (sall-Allahu alayhi wa-sallam - may the blessings and peace of Allah be upon him) 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:  Al-Hadid;  Al-Hashr;  As-Saff;  Jumu'ah; and  At-Taghabun.
“Having cited this Hadith, Ibn Kathir says that the best verse referred to in Surah Al-Hadid is verse  ‘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 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]
Al-Hilali, M. T., & Khan, M. M. (no date) The Noble Qur’an (Vol. 1). Riyadh, Saudi Arabia: Darussalam.
Shafi, Maulana Mufti M. (2009) Ma’ariful-Qur’an. (7th English ed.) (Vol. 1). Karachi, Pakistan: Maktaba-e-Darul- Uloom Karachi.
“Sajdah (pl. Sujud): The act of prostration in the prayer, when seven portions of the body touch the earth: the forehead on pure ground, two palms, two knees and the two big toes. . .” Jami’ At-Tirmidhi (1st ed. November 2007). (Vol. 6 – Glossary of Islamic Terms p. 627). Riyadh, Saudi Arabia: Darussalam.