Hadith 1268
Ibn `Umar (May Allah be pleased with them) reported:
عن ابن عمر رضي الله عنهما، قال: كان رسول الله صلى الله عليه وسلم يعتكف العشر الأواخر من رمضان. ((متفق عليه))
The Messenger of Allah (ﷺ) used to observe I`tikaf in the last ten days of Ramadan. [Al-Bukhari and Muslim].
In plain words
The Prophet would seclude himself in worship during the last ten days of Ramadan. It points to these final days as a special time to intensify devotion.
Reference : Riyad as-Salihin 1268 In-book reference : Book 9, Hadith 1