عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ رَضِيَ اللَّهُ عَنْهُ أَنَّ رَجُلًا أَتَى النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ فَقَالَ: يَا نَبِيَّ اللَّهِ! إِنِّي شَيْخٌ عَلِيلٌ، يَشُقُّ عَلَيَّ الْقِيَامُ فَأْمُرْنِي بِلَيْلَةٍ لَعَلَّ اللَّهَ يُوَفِّقُنِي فِيهَا لِلَيْلَةِ الْقَدْرِ، قَالَ: ((عَلَيْكَ بِالسَّابِعَةِ))
It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) that a man came to the service of the Noble Prophet (peace and blessings be upon him) and said: O Messenger of Allah! I am an old and sick man, it is difficult for me to stand (in prayer), so please specify one night for me, perhaps Allah Almighty will bless me with the fortune of Laylat al-Qadr in it. The Prophet (peace and blessings be upon him) said: Make special arrangements for the seventh, that is, the twenty-seventh night.