عَنْ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ رَضِيَ اللَّهُ عَنْهُ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ إِذَا صَلَّى الْعِشَاءَ رَكَعَ أَرْبَعَ رَكَعَاتٍ وَأَوْتَرَ بِسَجْدَةٍ ثُمَّ نَامَ حَتَّى يُصَلِّيَ بَعْدُ صَلَاتَهُ بِاللَّيْلِ
Sayyiduna Abdullah bin Zubair (may Allah be pleased with him) says that when the Messenger of Allah (peace and blessings be upon him) would perform the Isha prayer, he would offer four rak'ahs and also perform one rak'ah of Witr, and then he would sleep. Later in the night, he would perform his (additional) prayer.