They used to sleep but little of the night, (51:17)

Almuntakhab Fi Tafsir Alquran Alkarim

They hardly missed a night but apportioned part of it, be it little or much, to divine worship at the expense of their sleep

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(51:17) they used to sleep but little by night, *15

They used to sleep but little of the night, meaning

*15) Some commentators have given this meaning of this verse: "Seldom did it so happen that they spent the whole night sleeping and did not spend a part of it, in the beginning of the night or in the middle or in the end of it, awake in the worship of Allah. " This commentary with a little variation in wording has been related from Hadrat lbn "Abbas, Anas bin Malik, Muhammad al-Baqir, Mutrif bin 'Abdullah, Abul 'Aliyah, Mujahid, Qatadah, Rabi` bin Anas and others. According to some other commentators, it means this: "They spent the major part of their nights in the worship of Allah Almighty and slept little. " This meaning has been reported from Hadrat Hasan Basri, Ahnaf bin Qais, and Ibn Shihab Zuhri, and the later commentators and translators have preferred this, for this appears to be in better agreement' with the words of the verse and the context. That is why we have adopted this meaning in the translation.
 

They used to sleep but little of the night, meaning in Urdu

راتوں کو کم ہی سوتے تھے