I said to Ubayy b. Ka'b: Tell me about lailat al-qadr, O Abu al-Mundhir, for our companion (Ibn Mas'ud) was questioned about it, and he said: Anyone who gets up for prayer every night all the year round will hit upon it (i.e. lailat al-qadr). He replied: May Allah have mercy on Abu 'Abd al-Rahman. By Allah, he knew that it was in Ramadan, (Musaddad's version goes) but he disliked that the people should content themselves (with that night alone); or he liked that the people should not content themselves (with the night alone). According to the agreed version: By Allah, it is the twenty-seventh night of Ramadan, without any reservation. I said: How did you know that, Abu al-Mundhir? He replied: By the indication (or sign) of which the Messenger of Allah ﷺ informed us. I asked Zirr: What is the sign ? He replied: The sun rises like a vessel of water in the morning following that night; it has no rays until it rises high up. (Using translation from Abū Dāʾūd 1378)
«رَحِمَ اللهُ أَبَا عَبْدِ الرَّحْمَنِ أَمَا وَاللهِ لَقَدْ عَلِمَ أَنَّهَا فِي رَمَضَانَ وَلَكِنَّهُ كَرِهَ أَنْ يَتَّكِلُوا أَوْ أَحَبَّ أَنْ لَا يَتَّكِلُوا وَاللهِ إِنَّهَا لَفِي رَمَضَانَ وَإِنَّهَا لَيْلَةُ سَبْعٍ وَعِشْرِينَ يَحْلِفُ وَلَا يَسْتَثْنِي» قَالَ قُلْتُ يَا أَبَا الْمُنْذِرِ أَنَّى عَلِمْتَ ذَلِكَ؟ قَالَ «بِالْآيَةِ الَّتِي أَخْبَرَنَا رَسُولُ اللهِ ﷺ» قَالَ حَمَّادٌ فَقُلْتُ لِعَاصِمٍ مَا الْآيَةُ؟ قَالَ «تُصْبِحُ الشَّمْسُ صَبِيحَةَ تِلْكَ اللَّيْلَةِ لَيْسَ لَهَا شُعَاعُ مِثْلَ الطَّسْتِ حَتَّى تَرْتَفِعَ»