73:20
اِنَّ رَبَّکَ یَعۡلَمُ اَنَّکَ تَقُوۡمُ اَدۡنٰی مِنۡ ثُلُثَیِ الَّیۡلِ وَ نِصۡفَہٗ وَ ثُلُثَہٗ وَ طَآئِفَۃٌ مِّنَ الَّذِیۡنَ مَعَکَ ؕ وَ اللّٰہُ یُقَدِّرُ الَّیۡلَ وَ النَّہَارَ ؕ عَلِمَ اَنۡ لَّنۡ تُحۡصُوۡہُ فَتَابَ عَلَیۡکُمۡ فَاقۡرَءُوۡا مَا تَیَسَّرَ مِنَ الۡقُرۡاٰنِ ؕ عَلِمَ اَنۡ سَیَکُوۡنُ مِنۡکُمۡ مَّرۡضٰی ۙ وَ اٰخَرُوۡنَ یَضۡرِبُوۡنَ فِی الۡاَرۡضِ یَبۡتَغُوۡنَ مِنۡ فَضۡلِ اللّٰہِ ۙ وَ اٰخَرُوۡنَ یُقَاتِلُوۡنَ فِیۡ سَبِیۡلِ اللّٰہِ ۫ۖ فَاقۡرَءُوۡا مَا تَیَسَّرَ مِنۡہُ ۙ وَ اَقِیۡمُوا الصَّلٰوۃَ وَ اٰتُوا الزَّکٰوۃَ وَ اَقۡرِضُوا اللّٰہَ قَرۡضًا حَسَنًا ؕ وَ مَا تُقَدِّمُوۡا لِاَنۡفُسِکُمۡ مِّنۡ خَیۡرٍ تَجِدُوۡہُ عِنۡدَ اللّٰہِ ہُوَ خَیۡرًا وَّ اَعۡظَمَ اَجۡرًا ؕ وَ اسۡتَغۡفِرُوا اللّٰہَ ؕ اِنَّ اللّٰہَ غَفُوۡرٌ رَّحِیۡمٌ ﴿٪۲۰﴾
Your Lord knows indeed that you pass in prayer nearly two-thirds of the night, and (sometimes) half of it, and (sometimes) a third of it, as do a group of those with you. And Allah measures the night and the day. He knows that (all of) you are not able to do it, so He has turned to you (mercifully); so read of the Quran whatever is easy for you. He knows that there are sick among you, and others who travel in the land seeking of Allah’s bounty, and others who fight in Allah’s way. So read as much of it as is easy (for you), and keep up prayer and give the due charity and offer to Allah a goodly gift. And whatever of good you send on beforehand for yourselves, you will find it with Allah — that is best and greatest in reward. And ask forgiveness of Allah. Surely Allah is Forgiving, Merciful.
The Holy Prophet and those with him passed sometimes two-thirds, sometimes a half, and sometimes a third of the night in prayer. All Muslims could not follow their example, and hence they are told that they might pray by night so long as it was easy to them and not a burden. By the reading of the Quran is here meant its recital in the night-prayer called tahajjud.