Mishkat al-Masabih 7 Fasting كتاب الصوم 126

وَعَن ابْن عمر قَالَ: أَنَّ رَجُلًا مِنْ أَصْحَابِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أُرُوا لَيْلَةَ الْقَدْرِ فِي الْمَنَامِ فِي السَّبْعِ الْأَوَاخِرِ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «أَرَى رُؤْيَاكُمْ قَدْ تَوَاطَأَتْ فِي السَّبْعِ الْأَوَاخِرِ فَمَنْ كَانَ مُتَحَرِّيهَا فَلْيَتَحَرَّهَا فِي السَّبْعِ الْأَوَاخِر»

Ibn ‘Umar said that some of the Prophet’s companions had a dream that lailat al-qadr was among the last seven nights, so God’s messenger said, “ I see that your dreams agree regarding the last seven nights, so if anyone seeks it he should do so during the last seven nights.” (Bukhari and Muslim.)