I heard from Ubayy b. Ka'b a statement made by 'Abdullah b. Mas'ud in which he said: He who gets up for prayer (every night) during the year will hit upon Lailat-ul-Qadr. Ubayy said: By Allah I there is no god but He, that (Lailat-ul-Qadr) is in Ramadhan (He swore without reservation: ) By Allah, I know the night; it is the night on which the Messenger of Allah ﷺ commanded us to pray. It is that which precedes the morning of twenty-seventy and its indication is that the sun rises bright on that day without rays.  

أُبَىٌّ وَاللَّهِ الَّذِي لاَ إِلَهَ إِلاَّ هُوَ إِنَّهَا لَفِي رَمَضَانَ يَحْلِفُ مَا يَسْتَثْنِي وَوَاللَّهِ إِنِّي لأَعْلَمُ أَىُّ لَيْلَةٍ هِيَ هِيَ اللَّيْلَةُ الَّتِي أَمَرَنَا بِهَا رَسُولُ اللَّهِ ﷺ بِقِيَامِهَا هِيَ لَيْلَةُ صَبِيحَةِ سَبْعٍ وَعِشْرِينَ وَأَمَارَتُهَا أَنْ تَطْلُعَ الشَّمْسُ فِي صَبِيحَةِ يَوْمِهَا بَيْضَاءَ لاَ شُعَاعَ لَهَا