Translation:

49. And for part of the night also praise thou Him and at the retreat of the stars!

Notes (Tafseer)

5083. It is not necessary to understand this for any particular canonical prayers. It is good to spend a part of the night in prayer and praise: Cf. lxxiii. 6. And the Dawn is a daily recurring miracle, full of spiritual influences and "testimony": Cf. xvii. 78-79.

5084. Idbar-un-nujum: the setting of the stars: the glorious hour of early dawn. In cxiii. 1, we seek Allah's protection as "Lord of the Dawn".