They used to sleep but little at night.
The scholars of Tafsir have two opinions about this;
The First Opinion
The first is that, they used to spend a little part of every night awake.
Ibn Abbas said,
"Every night, they would worship Allah, even during a little part of the night."
Qatadah narrated that Mutarrif bin Abdullah said,
"Hardly a night would pass by them that they did not pray to Allah the Exalted and Most Honored, either in the beginning, or the middle of it."
Mujahid said,
"Only a few nights, if any, would they sleep through the night until the morning without praying Tahajjud."
Qatadah said similarly.
Anas bin Malik and Abu Al-Aliyah said,
"They used to pray between Al-Maghrib and Al-`Isha'."
The Second Opinion
They used to spend a little part of the night in sleep. This was preferred by Ibn Jarir.
Al-Hasan Al-Basri said;
كَانُوا قَلِيلًا مِّنَ اللَّيْلِ مَا يَهْجَعُونَ
(They used to sleep but little by night),
"They performed voluntary night prayer and would not sleep during the night except a little. They were active and would continue until they were seeking forgiveness right before dawn."
Abdullah bin Salam said,
"When the Messenger of Allah arrived at Al-Madinah, people quickly gathered around him and I was among them. When I saw his face, I knew that it was not the face of a liar. The first statement I heard from him was,
يَا أَيُّهَا النَّاسُ
أَطْعِمُوا الطَّعَامَ
وَصِلُوا الاَْرْحَامَ
وَأَفْشُوا السَّلَأمَ
وَصَلُّوا بِاللَّيْلِ وَالنَّاسُ نِيَامٌ
تَدْخُلُوا الْجَنَّةَ بِسَلَم
O people!
Feed with food,
keep relations to kith and kin,
spread the Salam,
pray at night while people are asleep,
and you will enter Paradise in peace."
Imam Ahmad recorded that Abdullah bin Umar said that the Messenger of Allah said,
إِنَّ فِي الْجَنَّةِ غُرَفًا يُرَى ظَاهِرُهَا مِنْ بَاطِنِهَا وَبَاطِنُهَا مِنْ ظَاهِرِهَا
Verily, there are lofty rooms in Paradise in which their outside can be seen from inside and their inside from the outside.
Abu Musa Al-Ash`ari said, "Who are they for, O Allah's Messenger" He said,
لِمَنْ
أَلَانَ الْكَلَمَ
وَأَطْعَمَ الطَّعَامَ
وَبَاتَ للهِ قَايِمًا وَالنَّاسُ نِيَام
For those
who use soft speech,
feed food and
spend the night in voluntary prayer while people are asleep.
Allah said;
وَبِالاَْسْحَارِ هُمْ يَسْتَغْفِرُونَ