Sunan Ibn Majah Book 2, Hadith 692

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا خَالِدُ بْنُ الْحَارِثِ، حَدَّثَنَا حُمَيْدٌ، قَالَ سُئِلَ أَنَسُ بْنُ مَالِكٍ هَلِ اتَّخَذَ النَّبِيُّ ـ صلى الله عليه وسلم ـ خَاتَمًا قَالَ نَعَمْ أَخَّرَ لَيْلَةً الْعِشَاءَ الآخِرَةَ إِلَى قَرِيبٍ مِنْ شَطْرِ اللَّيْلِ فَلَمَّا صَلَّى أَقْبَلَ عَلَيْنَا بِوَجْهِهِ فَقَالَ ‏ "‏ إِنَّ النَّاسَ قَدْ صَلَّوْا وَنَامُوا وَإِنَّكُمْ لَنْ تَزَالُوا فِي صَلاَةٍ مَا انْتَظَرْتُمُ الصَّلاَةَ ‏"‏ ‏.‏ قَالَ أَنَسٌ كَأَنِّي أَنْظُرُ إِلَى وَبِيصِ خَاتَمِهِ ‏.‏

Humaid said:"Anas bin Malik was asked: 'Did the Prophet wear a ring?' He said: 'Yes.' One night he delayed the 'Isha' prayer until almost the middle of the night. When he had prayed, he turned to face us and said: 'The people have prayed and gone to sleep, but you will still be in a state of prayer so long as you are waiting for the (next) prayer.'" (Sahih)Anas said: "It was as if I can see the sparkle from his ring