Narrated by Sayyidah Aisha (may Allah be pleased with her): When the last ten days (of Ramadan) would begin, the Prophet Muhammad (peace be upon him) would tighten his waist-wrapper (i.e., he would prepare himself with full determination), and he would stay awake during the nights and also wake up his family members.
Hadith Referenceاللؤلؤ والمرجان / كتاب الاعتكاف / 730
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 32 كتاب فضل ليلة القدر: 5 باب العمل في العشر الأواخر من رمضان»
Brief Explanation
The meaning of "tightening the waist belt" is that during this ten-day period, you would exert special effort in the worship of Allah. You yourself would stay awake, awaken your family members, and remain engaged in the worship of Allah throughout the night. (Raaz)