They glorify Him by night and day (proclaiming that He is absolutely exalted above any shortcoming or need of partners or doing pointless things), and never show tiredness and never lose zeal
The night and the day they glorify (tasbih) Him (by fulfilling their creational purpose) continually!
Sayyed Abbas Sadr-Ameli
They glorify (Him) by night and day; they never intermit
Al-muntakhab fi tafsir al-Qur'an al-Karim
They .celebrate and glorify their Creator and extol His glorious attributes night and day and they never lose vigour, grow dull nor do they lose interest
And whoever (or whatever) is in the skies and the earth is His and those who are with Him do not consider themselves great to serve Him nor/are they tired.