عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ يَعْتَكِفُ فِي الْعَشْرِ الْأَوَاخِرِ وَيَقُولُ: ((الْتَمِسُوهَا فِي الْعَشْرِ الْأَوَاخِرِ)) يَعْنِي لَيْلَةَ الْقَدْرِ
It is narrated from Sayyidah Aisha (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) used to observe i'tikaf in the last ten days, and he used to say: "Seek the Night of Qadr in the last ten nights."